SIO335: Are There Morning People and Night People? What the Science Says

Transcript

This transcript was generated automatically and may contain errors — the audio is the record.

0:00:11 Thomas: Hello and welcome to Serious Inquiries Only. This is episode 335, allegedly. Thomas, that's Lindsey. We're both groggy because it's noon. No, and we decided it'd be good, like, tie-in to the episode if we both, you know, truly didn't sleep well because we're not morning people, because we're going to be talking about, uh, morning versus day, man versus night, night man, champion of the, how are you doing today? Yeah.

0:00:21 Lindsey: Indeed. Yeah, and karate and friendship. It's very exciting. Yeah. Oh, man. I things are dark, I guess, but, but I'm excited. I'm excited about the fun science thingy. It is gonna be fun.

0:00:47 Thomas: Well, It's, this is perfect timing for this episode because, um, struggling, I might have mentioned it on a show, I'm struggling with Arlo again, with the, he's just, he's a morning dude, he's, He's a morning dude. We're in the middle of just trying to get the slightest compromise going, like just a little bit of... wants, So to wake up at five, six, and just be ready to start his day. And that sucks. That's not compatible with life on this planet.

0:00:57 Lindsey: Hmm. Yeah?

0:01:20 Thomas: And so I'm trying to do a thing. We already had... Like we used to have the clock that turns green and tells them to come out, you know, that's a cool, but like, we kind of forgot about it. Cause they just, I don't know. They just ignored it. Or I think Arlo was too small to understand it for a while. So we kind OF forgot about. But we, I was like, okay, we got to try to do that. We have to try and do it compromise, you know, 7:45 AM that that's like, you know, that's still pretty early. It's really early for me, but it's still, still early.

And we, he can't do it. He comes in at round, at the latest, like 6:45 or 7 a.m., he just comes and beats on the door and screams like he's dying and like, we've abandoned my boy. And this is, it's, I don't know what to do. So I've tried all these methods I've got. I've, I tried like setting out his food, like ready for him to get to, you know, and, but it's all just excuses. He really just, he just wants to be around his mom. Like it's everything else is, It's amazing kids come up with a lot of pretexts. Oh, I'm hungry and I can't open the thing. It's all bullshit.

0:01:46 Lindsey: Yeah. Yeah

0:02:24 Thomas: He just wants to be around his mom.

0:02:24 Lindsey: It is. Yeah, they just love you. That's terrible.

0:02:26 Thomas: Yep. No, not me. Just his mom, no,

0:02:31 Lindsey: So, so Phoebe was not like this? She was not not similarly timed?

0:02:34 Thomas: I don't, Phoebe early, but she would just sit and just, which is weird because she's actually the more dependent person. It doesn't make any sense. None of it makes any sense, Lindsay. She's the more like social dependent, needy person. And Arlo, historically, it may just be a phase. Everything is like, oh, well, it's the phase where they do such and such, you know? Maybe this is just the phase where like he's super clingy. I think toddlers go through that phase because it used to be you plonk this boy down in front of some puzzles and he'll just do puzzles forever, not care about anything about me, anything.

But no, in the morning he has to. Phoebe used to, it was delightful. We'd hear her like nonsense babbling. You know, we kind of have the monitor on a little bit and we just hear these like little, it's the most delightful thing in the world. Not the reason you're doing this episode, but let's pretend it is. So I've enlisted Lindsay to research what's going on. Are people just morning people? I've always firmly believed that people are either morning people or night people because I'm firmly a night person and

0:03:02 Lindsey: Yeah, for sure.

0:03:38 Thomas: I can't. I cannot wake up in the morning, no matter what I do the best, the best thing I can do is if I've ever gotten a job, that's like, you know, requires waking up super early is I do it. And I'm just fucking miserable all the time.

0:03:51 Lindsey: All the time.

0:03:52 Thomas: Yeah. Never ending misery. And that can't be right. That can't be like everybody just is the same. And we all feel it has to be. Cause I know people Like my sister, other people are like, yeah, I just pop up at like 5:00 AM. Like, what the fuck are you you talking about, that's impossible, there's no way that that is real. Uh, so all that babbling aside, sorry, I'm exhausted from being woken up by my boy. All that babbling aside, Lindsey, what, what does the science say? Take us through it.

0:03:53 Lindsey: Yep. Yep, mm -hmm.

0:04:21 Lindsey: Yeah, no, there's definitely some differences here, but it's nuanced. It's nuanced and science -y, so it's going to be really fun. But I Think, so this has got to be a two-parter because I had so much fun with this prep. There's some topics we do that I just can't stop reading stuff about it. So today we're going going to lay out what these individual differences look like and what causes them. But it's this part two that I think is really going to get to the source of your frustration, which is that I think that we live in a world that privileges morning types,

0:04:24 Thomas: Oh. I- Hate nuance.

0:04:55 Lindsey: And that There's a Lot of chronotype Chauvinism in this society.

0:04:55 Thomas: You're- Goddamn- Right. God- So you're saying I shouldn't yell about that, right? Okay, I will will hold my yelling for that if that's part two.

0:05:03 Lindsey: Yeah. Yeah, no, but that's good. I'm glad that we're starting with that. I think that that's a good preview. The science word for what you're talking about, out, the night owls versus the morning people, is chronotype, which makes sense, right? Chrono, time, and then types, I guess. So chronotype just refers to sleep timing. So it's independent of like how long you sleep or how well you sleep. You can absolutely be a super evening type or a super morning type and get equally sufficient high quality sleep.

0:05:17 Thomas: Yeah. Huh.

0:05:31 Lindsey: Chronotype is just about when you tend to do it. I've always found these individual differences really interesting and, you some stuff about it in grad school. And then, you know, occasionally you run into like a popular press article that talks about these types. I don't know if you've seen these. It's like usually like in the health section or something.

0:05:45 Thomas: I tend to ignore all of those, but, but you do see, you know, memes. I get my news in meme form. I give my health.

0:05:47 Lindsey: Yeah, well, good. Oh, OK.

0:05:52 Thomas: No, not really. I also ignore that, but I imagine it's the same kind of thing.

0:05:57 Lindsey: I mean, it's sometimes I see treatments of it that are pretty decent, and a lot of times I see stuff that really seems to to veer into like woo territory, so

0:06:05 Thomas: Well, I'll tell you what I always see and what everybody always sees, and that I think most people listening and, you know, of a certain type and politics would agree with, is that high school starts way too early, you know, you'll see that's like the popular way that you'll come across, as kids in high, especially in high school, need to be sleeping until like 10 a.m. for development and everything would be better if they just did that, and also, uh, can't believe we're forgetting to mention this until now, the fucking time changes. That's what actually, now.

Now that I remember, because our brains are mush, that's what launched this whole thing. I think we're like talking about the time changes and like what, you know, is what is the best way? Because I was firmly on that like the best thing would be just keep daylight savings time permanent. But then I heard some like actual sciencey podcasts and people being like, it's a little more complicated than that. But I still I don't believe that. And of that conversation was, well, if you're worried about schools School's going, buses and all that going in the dark in the morning. Just make school start later. And

0:06:22 Lindsey: That's true. Oh, my God, yeah. Oh, was it oh that's right, yep yes

0:07:03 Thomas: So anyway, that's where I imagine a lot of people have come across this.

0:07:07 Lindsey: Absolutely, so yeah, I've seen that a lot too, and that that is, that is absolutely true. And it's fairly recent that that has has sort of been the response about, um, school timing in particular. Like, there was a real kind, kind of like, kids these days kind of attitude about adolescent sleep cycles for a long time. And like, no, I mean, we're gonna talk about this a little bit later. But like, no, there are really right. And it's not just a human thing either. So in a lot of species, you see this change in sleep timing that happens around the time of puberty, or like sexual maturity or whatever. It's just kids being hooligans, which I think is, yeah.

0:07:20 Thomas: Yeah.

0:07:39 Thomas: Interesting. Put a pin in this question, but now I wonder, is Arlo subject to change? Or is he just a... Okay, so it's not like you're born with a type and you kind of...

0:07:46 Lindsey: Oh, Oh, for sure. Well, it's both, right?

0:07:52 Thomas: It's both. Okay. So he's going to be a pain in my ass for the rest... No, eventually he'll get less interested in us and I'll just be like, I'll wake up and play, you know, play a video game or something.

0:07:52 Lindsey: So like, yes, Arlo will change. Well. Well, so the thing that you're describing, I don't think is actually a problem with his chronotype, right. So did you get the sense that he wakes up earlier than Phoebe or just that he wants.

0:08:08 Thomas: Absolutely. Yes. He wakes up into the I should have mentioned that to the point where Phoebe and I it's it's hard. You know, you Know, siblings fight all the time. It's the it's breaks your heart. It's really tough because they just hit each other. Whatever, she part of what will be the tantrum of Arlo waking up early is he wakes up early and is loud and wakes Phoebe up and Phoebe hits him because she's so annoyed at being woken up early. And I'm like, you shouldn't do that, Phoebe. I fully understand, but you should not ever hit anybody all the time. That being said, I'm not that super mad at you because when you're a toddler and someone's waking you up, you don't have, you already have limited self -control as a toddler at all. And then somebody's freaking waking you up at 5 a.m. Like, I don't know, that's one where it's like, I's sad that this is happening, but it's hard to be that mad at Phoebe for not being able to control herself in that moment.

0:08:09 Lindsey: Oh, OK. OK. Yeah. Oh God. Yeah,

0:08:56 Thomas: So yeah, no, he's just wakes up early. He's just ready to fucking go and nobody else in the house is even Lydia. Hmm.

0:08:57 Lindsey: Yeah. OK, that's interesting. So he will shift over the course of his life. But it's also probably the case that he's always going to be more of a morning person than the rest of you are, is my guess. There's lots of things. I can't wait to get into it. It's fun. I've seen this covered in the popular press, I see two kinds of errors being made a lot of the time. So one version of the article that I see is like veering too much into this territory that it's it's almost like astrology or like intimate or internet quiz typology kind of thing. Like I found, I found one that instead of talking about evening people and morning people, they created this new typology of bears, wolves, lions, and dolphins to describe sleep types and like talked about it in the sense that like really sounds like, you know, sleep destiny type stuff.

0:09:08 Thomas: Okay. Oh. Yeah. Uh.

0:09:46 Thomas: Like All right. Yeah. I'm

0:09:52 Lindsey: Yeah, yeah, and that's not. Oh.

0:09:53 Thomas: An alpha Dolphin, that's my sleep type. Yeah.

0:09:56 Lindsey: The dolphin was the weirdest one too, because like, okay, so so wolves were evening types, lions were morning people. But dolphins just sounded like anybody who has like an undiagnosed sleep condition. It was very weird. I no idea where that came from. But anyway, so that was weird. That has its own problems. But then the other side of that that I see in other representations is articles treating sleep like it's entirely a choice or sleep timing, as though it's entirely a choose and giving. Yeah, yeah. And giving people advice.

0:10:21 Thomas: Abso -fucking-lutely not here I ran a little experiment for you. No, no.

0:10:28 Lindsey: It's really not. Yeah. Yeah. So like most things, it's both, right? There are definitely sort of predispositions that change the way that your circadian rhythms work, essentially. So the actual research on this stuff is just super cool, and we should talk about it now, for sure. Yeah. So today I thought we could start with what chronotype is, what modulates it, how biologically fixed or flexible it is. And then, yeah, we're going to talk about some of the developmental changes, which I think will speak to the stuff you're asking about your kids. There's some gender difference stuff with chronotype that's pretty cool. Then, yeah, part two is going to be about like things that are associated with chronotype and like the chauvinism against evening types that exist in society.

0:10:29 Thomas: Yeah. Absolutely. Yeah.

0:11:05 Thomas: And We're gonna start a fucking revolution on this show. Thank

0:11:10 Lindsey: Absolutely. Yeah, the answer to all of this stuff is just that we need to completely restructure society so that it doesn't suck so much.

0:11:16 Thomas: You.

0:11:16 Lindsey: I mean, yeah. Great. Let's start with the distribution of chronotypes in humans. So how much do we differ from each other when it comes to when we go to sleep and when we wake up or when we prefer to do that? Talked about early birds and night owls already. The majority of people are actually neither. They're kind of intermediate. So they aren't particularly morning or evening inclined. So like most traits, chronotype is like roughly normally distributed. It's like on a bell curve.

0:11:42 Thomas: Oh. Okay. Okay.

0:11:44 Lindsey: Yeah. So the modal or the most commonly preferred sleep period starts somewhere between 11 p.m. and midnight, and then ends between like 7 and 8 a.m. So like two-thirds of folks fall into that category, their sleep is is sort of around that period. Um,

0:11:59 Thomas: That sounds like a morning person to me. Oh.

0:12:02 Lindsey: Yeah, but I think that you're particularly, I think you're in a very extreme tale. Um,

0:12:07 Thomas: Okay. What so then what, okay, so are you telling me there's people who wake up at 8 a.m. and they're like, god, I fucking, I can't wake up in the morning, I can't wake up until 8 a.m., and other people are like, yeah, you should be up at six, like me. Oh my God. All right. Well, I'll just leave. I guess I'm not meant to be here in society.

0:12:07 Lindsey: Yeah. Uh Yeah. We're gonna fix it. We're gonna fix at all, yeah, let's talk about this a little bit. So our own chronotypes, that is, is the kind of thing that people can self-report pretty accurately, by the way. So it's just asking people, do you think you're more of an evening or morning type, is actually a pretty valid way to get a sense of where people are. So you've already self-identified as an evening type. How different from the average do you think you are based on your experiences?

0:12:28 Thomas: Okay. Huh?

0:12:49 Thomas: Do I express that? Like what, in what ways, terms do I express that difference?

0:12:53 Lindsey: Like much later do you think your preferred bedtime is compared to most people Yeah.

0:12:56 Thomas: Then normal people.

0:13:02 Lindsey: So when is that, actually, so like, if you could, if you weren't sleep deprived and you could go to bed whenever you wanted, wake up whenever you want it was that look like

0:13:06 Thomas: I So what happens to me is at nighttime, I become awake. Finally, I am, I'm tired all day and the morning's impossible. I go from in the morning, I go From something's wrong with me. Like, I think I need to go to the hospital in the morning and then by afternoon, I guess I'm just tired. And then by evening, I I'm full of energy. Let's start our day and I feel great.

0:13:31 Lindsey: Yeah.

0:13:31 Thomas: And then I want to stay up because that's when I actually feel good. And I could, I literally could stay up forever. Ever. Like there's no, I mean, I get this probably not literally true, but like I don't get to a point where I'm tired at night. I go, well, I guess I have to be a member of society. So I'll fucking go to bed and try. And also I guess my, you son's going to shit his pants at 5am. So like if I took away all those concerns, I actually truly don't know what my time would be.

0:13:35 Lindsey: Mm -hmm.

0:13:57 Lindsey: Interesting.

0:13:57 Thomas: Like it would, it might be like 3am to 11am if I'm being honest.

0:13:58 Lindsey: Interesting Huh, okay, so I think you are in a pretty extreme tale actually, I was, because, you know, the kids thing does, I mean, we'll get into some of this, like, I think that some people might have trouble knowing when their preferred sleep and wake times are because of like work constraints because they have kids or whatever but you're saying you're saying that there's like, there's... there's been no point in your life when you've been on a on a schedule that actually feels like it fits with with where you're supposed to be right

0:14:10 Thomas: Yeah. Yeah. Kids screaming in their ear at fucking, sorry. No, mean I became a podcaster, so I got to, so when I became a podcaster and didn't have kids for that brief glorious window of time, well, no, but then I also, I still was married and I didn't like the fact that like, I don't want to not have any time with Lydia. So like she would need to go to bed. And if I stayed up forever, then it's like, you know, I'm not awake in the morning. And then at night I'm, you Know, I do, I want to have more time together. So I still don't truly know, like if I was just left to my own devices, but I would easily wait, like 1030 is like my wake up time. Probably.

0:14:33 Lindsey: I'm sure that helped uh -huh Okay.

0:15:03 Lindsey: And you still feel like exhausted at 10:30? Okay.

0:15:07 Thomas: 1030. I can't, I can feel okay. Actually. I shouldn't Have said that, but it's, I, that when I said, I feel like I need to go to the hospital in the the morning. That's when I've been woken up once by Arlo and then try to go back to sleep and then have to wake up at like, you know, nine 30 or 10 after being interrupted, you know, like, so that doesn't work.

0:15:10 Lindsey: Right okay okay no, this is this is helpful. Okay. All right, cool, all I do, I do think you're an extreme tale, um, but, uh, yeah, yeah, okay, so we're gonna talk about some measurement things that I think are gonna maybe be insightful here. This is this is fun. Um, right, yeah, yeah, I did, that's a good idea. Yeah. So I definitely am more evening inclined than average, but not as extreme as you. So when left to my own devices, the cycle that I default to is probably like an hour and a half later than average. So like 1am to 9am, something like that.

0:15:24 Thomas: Okay. Diagnose me.

0:15:37 Thomas: About you? Do you want to tell us what your sleep is?

0:15:56 Thomas: Right.

0:15:57 Lindsey: That's not, until very recently, that wasn't a cycle that I've been able to be on for like a decade because work, right? And so So I kind of – I say that I've gotten used to it. I never quite got used to It. I was just in a perpetual state of sleep deprivation. But you could

0:16:02 Thomas: Yeah. Yeah, it's impossible. Yeah you get You get used to it in that you're just miserable and then you deal with it.

0:16:13 Lindsey: – yeah, exactly. It's terrible. And, you know, like I – even though I knew about some of the stuff, you do kind of forget that like you can't just control It. So I would – you know I was trying to force myself to go to bed at like 9:30 or 10 if I had to, you know, get up super early for work on a regular basis.

0:16:27 Thomas: Yeah. Oh, my God. I literally can't do

0:16:36 Lindsey: This. No, see, and that's the thing. And I and when I couldn't go to sleep, I would I was I would be like, man, I'm struggling with insomnia. Why can't I fall asleep? And yeah, since doing all this prep for the show, it's like, oh, yeah, of course, I couldn'T fucking fall asleep. Like, that's not. Yeah.

0:16:47 Thomas: That. No, that's impossible. That's not even possible. You saying that is like, I'm going to go to sleep for the night at 1 p .m. Why can't I go to bed? I must be an insomniac. That's like what it sounded like to me. Nine or ten. I would have to be dead. Like, there's been a couple times in my life I've been that tired if I, like, missed an entire night of sleep. Like, yeah, if I go a full all -nighter, then I can basically fall asleep at any time because I'm physically dead. But like a normal night, if I lay down at 9 or 10, my brain, my body would just laugh at me. Be like, what are you even doing? This is ridiculous.

0:16:58 Lindsey: Yeah, yeah.

0:17:14 Lindsey: Yeah see, And that's that's closer to what I'm back to now, right? The first time in a very long time. But like, again, I think that if you have been been on a schedule for years where you have, you know, you're just sort of constantly in a state of sleep deprivation. Plus, you add in drinking way too much caffeine throughout the day and then drinking a lot of alcohol at night.

0:17:30 Thomas: Mm-hmm. Sure.

0:17:42 Lindsey: And that can get you closer to regulating your cycles to where you want them to be, but it's not great. So that's kind of what I was doing.

0:17:43 Thomas: Yeah. I do the thing where I try tryと limit my caffeine just because of this very problem because I already won't be able to go to sleep. Sleep so I I do one nice solid pint of coffee in the morning and then I'm like anything more will fuck with my sleep at the at night because it's so hard for me to actually lay down. Yeah.

0:17:59 Lindsey: Right. Right. No, I did. I did similar things. So I would I would try to stop by like around noon or something, but then compensate with alcohol later. And that's not a great strategy. If anybody is curious, that's really not a good strategy.

0:18:18 Thomas: Yep. Not listening. I'm doing, no, I'm just kidding. Okay, so you're a night person, I might, I might be extreme night person, you're uh moderate night person, okay. Interesting.

0:18:28 Lindsey: Yes, I think that that's right. Yeah. Okay. All right. So let's let's get back to what the population looks like in general. And then we're going to talk about some some measurement stuff here. So so one of the oldest oldest and most widely used self -report measures of chronotype is called the Morning Eveningness Questionnaire. And it's available for people to take online if they're interested. I'll give you a link for the show notes. The MEQ, it's a really good measure. It's well validated. It converges strongly with more direct measures of sleep timing. Like for instance, when melatonin levels rise and fall throughout a 24 -hour period. So if people don't know, melatonin is a hormone that's involved in regulating, you know, sleep and wakefulness. And so it starts increasing about two hours before sleep onset, and it stays elevated during sleep, and then it starts declining about two hours before you wake up. So the melatonin peak, it's a really good indicator of sleep timing, and the MEQ predicts this strongly. Is also correlated with like accelerometer data.

0:19:24 Thomas: Accelerometer.

0:19:25 Lindsey: So this is studies where they use, yeah, so it's their devices that are are essentially like Fitbits. And so they track like periods of activity and sleep. And so that's, yeah, so it's like a really nice direct behavioral measure of these cycles, right? The fact that the MEQ correlates with these more direct measures indicates that it's capturing something meaningful about individual differences in sleep -wake times, right? So scores on this measure are 16 to 86. So you get like a certain number of points for your responses on the items, and then you sum them up to get your total score. The lower your score is, the more evening inclined you are, and the higher your score is, then more morning exactly. Yeah, it easily could have reversed that, but no, because morningness is better. Yeah, so higher scores mean more morningness. So a person with a score of 16 would basically be a vampire. Think it's actually extremely unusual for people to...

0:19:26 Thomas: Oh. Oh, oh. OK.

0:20:01 Thomas: Chauvinism already. Yeah.

0:20:17 Thomas: To be full nocturnal.

0:20:19 Lindsey: Yeah, yeah, right? Look at distributions of MEQ scores, I generally don't see people actually bottoming out the scale.

0:20:20 Thomas: OK. Yeah, that makes sense.

0:20:27 Lindsey: Yeah. So that's kind of a theoretical limit, I guess. But yeah, these would be people that prefer to, yes.

0:20:34 Thomas: Oh, also, wait, doesn't that mean you meet in the. Wouldn't you meet the other side? I was just thinking, like, what's the other extreme? A hundred. And then you're like, but you're also a vampire. So you go to, you would wake up so early that you, I guess it would be the difference between like your eight hours of sleep is like 8am to 4pm versus 4pm to midnight.

0:20:41 Lindsey: No.

0:20:58 Lindsey: So I think more realistically, it's more like super, super morning people would be like the most morning you could be would probably be getting up at the same time that the even most evening people are going to sleep, right? If if you prefer to go to bed at 5 a.m. or 4 a.n., let's say, no.

0:21:15 Thomas: No, think that would just be the extreme night person and a normal morning person, wouldn't it?

0:21:21 Lindsey: Well, yeah, so five, five is probably, you're right, they probably pass each other a little bit.

0:21:24 Thomas: No ,that's why I'm saying I think it's when you get your eight hour. So like the extreme morning person would wake out, let's say full extreme. They wake up at midnight. So like their nighttime was like 4 PM to midnight. The extreme night person, they go to bed at like 8 AM. Yeah. So it's still like, it's till nocturnal in quotes. Like they're still both awake at night, but like at different timings, one would be like starting their day at night and the other would be ending their day.

0:21:25 Lindsey: Yes. Right. Yeah. Yes.

0:21:53 Lindsey: Yeah, I think so. The reason I said realistically, though, is that is that when you actually look at the distribution of of sleep timing, it doesn't actually seem to line up. Like the the earliest morning people are like, like waking up at like, you know, the earliest would probably be like 4 a.m. without an alarm or something like that. Like that would be incredibly early. Theoretically, yeah. That would be true. Sort of the range of scores there. And people are categorized into five categories based on the score they get on the MEQ. Cue so

0:21:57 Thomas: Right. Yeah, yeah, yeah. Right. Well, I'm sorry. I just, in case I missed it, what was the realistically in the the data, the extreme night person, it was like go to bed like five or something or

0:22:21 Lindsey: Uh the limit that they put is like 2 to 3 a.m. or later so so that I seriously like I think that I think your patterns probably are sort of like the most in the most extreme tale sure

0:22:35 Thomas: Yeah I know people who stay up later than me, though, they, you know, they there are people because like I, yeah, again, though, I'm never tired, it's just that I'm like, okay, I guess I should be a human, so I don't really know, oh well, yeah

0:22:42 Lindsey: Yeah I but you know, so in part of what you were describing, it's like it's hard to sort out the effects of like when your preferred sleep schedule is and the effects of things like sleep deprivation and and misalignment, so I think that if you could, if you could like have a week where you sort of partialed all that other stuff out and could really see what your sleep like I would be interested to see like you felt most alert getting up and when you started to get tired I think you would actually start to see that emerge but yeah

0:23:05 Thomas: Mm -hmm yeah okay so we got the score we got got the vampires and the inverse vampires, whatever they are.

0:23:21 Lindsey: Okay yeah anti -vampires Fighter of the night mare, yeah, um, so we've got five different categories. They range from definite evening is what they call it, and that's the most extreme evening people. That would probably be you. You've got moderate evening, then intermediate, then moderate morning, and then definite morning, right? So we both took the MEQ. Do you remember what your score was?

0:23:25 Thomas: Yeah.

0:23:41 Thomas: 33. But I think I fudged it a little bit. I think, I think it went conservative.

0:23:45 Lindsey: Was actually a 39. So our scores, both of our scores kind of of put us near the boundary of two categories. So you were kind of between definite evening and moderate evening. And I was kind of Between moderate evening and intermediate.

0:23:57 Thomas: I bet 31 is more realistic. I, I, think I would have changed my mind about a couple of the questions.

0:24:02 Lindsey: Yeah, and there's some there's some issues with the MEQ that we'll talk about in a second that I think might resolve this a little bit. I, a revised version of it that I think you would definitely fall into the extreme category. So My my, that's very Very extreme.

0:24:05 Thomas: Ah, nice. Arlo scored a 497. the charts. The test just started glowing and then exploded when he took it.

0:24:20 Lindsey: Yeah. So even though you seem to think that this is like probably a higher score than you should probably have, even the score that you got is pretty extreme. So

0:24:30 Thomas: Oh. Really? Okay, well. Maybe it's not then, maybe it is the score I should have, I don't know.

0:24:30 Lindsey: Yeah, yeah. Yeah, I mean, so again, I was doing this based on a 31, but the 33 shouldn't be that much of a difference. So if you scored a 31, that puts you in a tail, depending on the sample that you're comparing yourself to. It puts you in a tail of like the most extreme one to 2%. If you get a score That, yeah, that's right.

0:24:51 Lindsey: It's Yeah, I know, it's just most people are like super intermediate, intermediate, everybody falls in that most, or you know, two-thirds of people fall in that, in that very intermediate category, um, so once you start getting out just even a couple hours from that, you're in a really extreme tale, yeah.

0:24:49 Thomas: Really? What's wrong with you people, yeah.

0:25:01 Thomas: Huh. God. This explains so much Like, I mean, there, it's just so much of society, well, I guess that'll be part two if I ever let you get to it. But like so much planning and whatever's like, yeah, well, no, we'll meet at like eight, and like, that's, what are you fucking talking about, we'll need it eight, it's possible we'll have to get Noah on. I think Noah's the only other, Noah Lusion's the only other person who's like super night person like me. Let's get him on and, normalize you it. Hashtag normalize, not fucking waking up at 5 a.m., you weirdos.

0:25:12 Lindsey: Yeah.

0:25:21 Lindsey: No, that, so that's fun, um, Know, now that I think about at it, I know a lot of atheist podcasters that seem to be on a pretty nighttime schedule. Uh-huh. So Yeah. I don't know. Maybe there's a research study in there somewhere.

0:25:40 Thomas: Ooh, yeah, Heath. Yeah, we're used to not matching up with the rest of fucking society.

0:25:49 Lindsey: There you go. That's what it is. Actually, there could be some real links there. Have to come back to that next time. Yeah, so even my score, which, you know, in terms of the scale is more moderate, like a 39, right, puts me at something like the 80th to 90th percentile for the measure overall. And again, I'm sort of very close to the edge of the moderate evening category. So it's, you know, it's fairly clustered in terms of how these things are distributed.

In terms of why you might have gotten a higher score than is your true score or whatever, I want to talk a little bit about some of the questions on the MAQ. So some of them are pretty pure measures of preferences, and others really aren't. I think that they seem to be be contaminated by other things. So some of the purer items are things like, approximately what time would you get up if you were entirely free to plan your day?

And then there's a symmetrical item: when would you go to bed if you're entirely free to plan your day? Like, those are, I think, capturing preference pretty exclusively, right?

0:26:46 Thomas: Yeah.

0:26:46 Lindsey: May Maybe be some error around that based on what's going on in your life. But I like those items. But then you have questions like So one of them is, if you have to get up at a specific time in the morning, how much do you depend on an alarm clock? Very

0:26:59 Thomas: There were a few like that and I'm glad that you're saying there's a problem here because there are a few like that where it didn't seem like there was an extreme enough answer. Mine was like one, it should be a hundred percent and the highest answer was like, uh, mostly or something. I thought. Yeah.

0:27:14 Lindsey: Much. Yeah.

0:27:14 Thomas: Very much. Like it's not enough, not enough of an answer. Yeah.

0:27:15 Lindsey: Mm hmm. Yeah, That's, that's actually true. I noticed that for a number of the response options that they don't actually have very extreme options, which is kind of interesting. Yeah?

0:27:24 Thomas: Yeah. It'll bias a little toward the day, day man. Yeah.

0:27:29 Lindsey: I think so. Right? Another problem I had with it is that, like, I could answer this question very differently based on what time in my life I'm accessing. So if I'm thinking back to semesters where, again, I had to get up at 6 a .m. to do what I needed to do to get to work, then like, yes, absolutely. Maxing that out very much. I'll take a more extreme option if I can have it.

0:27:50 Thomas: Well, Not only that, it depends on how important this thing is. Like if I have to get up for an airplane, I'm so anxious about it that, like, I'll just wake up, you know, but it's not, I'm not waking up like, ah, ready to start my airplane day. It's just like, ah, is it, oh fuck, do I go, and I feel like shit, you know, but I'm like, I think it's time to go to the airplane and miss my flight and have a horrible fucking travel day, which we did.

0:27:58 Lindsey: Yeah. Yeah. That's a whole other layer with the anxiety stuff, for sure. Know, so if I think back to times like that, like, yes, I depended on an alarm clock every day. There is no way I would have been able to get to work on time without an alarm clock. But like now it's like, okay, yeah, I want to get up at, say, you know, I, I absolutely have to be up by 10 a.m., right? I don't need an alarm clock, I can, I can, I will be up at 10 a.m. for sure. See, yeah.

0:28:13 Thomas: Yeah. Yeah.

0:28:35 Thomas: I kind of need one.

0:28:37 Lindsey: Nope, you're but again you're more extreme than I am.

0:28:37 Thomas: I would be like 50 50 50. I wouldn't be, I might wake up at 9:30, or I might not. Quite.

0:28:42 Lindsey: Okay, so your answer would change then, depending on the time that we're talking about. So maybe you do a somewhat

0:28:46 Thomas: Absolutely. Yeah Yeah, well, but if it's like 8 a.m., then a hundred percent. Yeah.

0:28:47 Lindsey: Yeah right Right, but that's kind of what I'm saying. So, like, all the question says is, if you have to get up at a specific time in the morning, how much do you depend

0:28:53 Thomas: Oh it didn't give you a time. I thought one of them gave you, like, it, there's one that was like, your friend wants to work out at 8 a.m. or something like that. Oh.

0:28:58 Lindsey: No, yeah. So so That one I liked better because it was tied to a specific time, this one isn't.

0:29:05 Thomas: Gotcha. Okay. Gotcha.

0:29:08 Lindsey: And so I do

0:29:09 Thomas: I see, I see what you're saying.

0:29:09 Lindsey: Think That questions like this on this scale reflect, I mean, you know, it does reflect something about like timing preferences for sleep, but it's also reflecting a lot of other things. It's reflecting probably your chronic level of sleep deprivation and the misalignment between your schedule and your preferred schedule. Thing that I think is interesting about this is that, again, the MEQ has pretty decent psychometric properties. So like it's pretty internally consistent. On the scale correlate with one another. And so if you gave the slightly morning response to the question about when you would go to bed, if you could plan your evening, then you're likely to also give that same sort of level of response on this thing about how much you depend on an alarm clock, right? Right. So the fact that you get that level of internal consistency, despite the fact that I think it's tapping multiple things, I think speaks to chronotype chauvinism.

0:29:48 Thomas: Yeah. Yeah.

0:30:04 Lindsey: Right. Suggests that people who are more evening type are more likely to have to get up at times in the morning when they're going to be, you not at their best. I think that's interesting. Right. I a paper that was validating a revised measure of this inventory. And essentially what they did was they did a factor analysis to try to figure out like what are the different dimensions that are being tapped by the scale and they identified five questions out of these 19 that seemed to be the best pure measures of sleep preference, right, and they're exactly the items you would think they are. So the items about like, you know, when would you get up and go to bed if you could choose that completely, how alert or tight or refreshed do you feel for When do you feel tired in the evening, and then at what time of day do you feel your best, right? And then, oh, this was a good item, the last item in the scale is just like a face valid self-report item of whether somebody considers themselves to be an evening type or a morning type.

0:30:09 Thomas: Totally. Okay.

0:31:00 Thomas: I thought it was gonna be like, how much do you fucking hate society for making you follow their rules. Yeah. Most days, every day. Yeah, okay.

0:31:04 Lindsey: Very Much. Yeah, slightly. Yeah, so so those, yeah. So those items, but not the other ones that we're talking about, that, like, could you, could respond to differently based on how much you can control your schedule. Those items really seem to, like, cluster together as the best pure measures of chronotype. And so when they did a validation study to compare, like, how people were categorized with this abbreviated measure versus the full one, they found that, like, I think it was about 20% of people were recategorized, and they tended to be people with scores that were like somewhat borderline between categories. And my guess is that if you were filling out only the items that I just talked about, that seemed to be this pure measure of preference, that you probably would have been solidly in the definitely evening type category.

0:31:37 Thomas: Interesting.

0:31:51 Thomas: Oh, I was wondering if there was a skew of, like, the people who revised were skewed more toward night people, because it wasn't capturing that as much. Oh.

0:31:59 Lindsey: Actually, it didn't seem to be associated with that, right? So people were miscategorized sort of across the thing.

0:32:03 Thomas: Okay, across the board.

0:32:07 Lindsey: It just, yeah. There was a couple of things, we don't have time for it, but like there were a couple of things about how they broke out the results there that were kind of interesting. And I think they do speak to the fact that the original MEQ is capturing, like, misalignment, in addition to these other things, but for another day, I guess. Yeah.

0:32:23 Lindsey: All right, so, so yeah, so there are problems with this measure, it's not to say that it's a terrible measure, right? I think that, again, it is capturing stuff because of the system that we all find ourselves in. So it's good, but, like, it's definitely capturing more than just these preferences. Another more recent measure of chronotype is called the Munich Chronotype Questionnaire. And this is much shorter and much simpler. And essentially, it's just asking people to estimate when they fall asleep and wake up on work days versus free days. And then using those estimates, researchers that use this measure estimate people's chronotype by taking their sleep times on free days and then adjusting them a little bit to account for the sleep debt that they accumulated during the work week.

0:32:22 Thomas: All Right. I Yeah.

0:33:05 Lindsey: Yeah, So, I really, I think this is a very cool measure. So the idea is that, like, sleep wake times on weekends are going to be closer to people's preferred circadian rhythm than on work days. Right. Their scoring method takes into account the fact that if your work schedule is severely misaligned with your preferred sleep schedule, then you're very likely to accumulate that sleep debt. And that's going to be reflected in a larger gap, essentially, between when you say you go to sleep.

0:33:05 Thomas: Yeah.

0:33:21 Thomas: I Got an adjustable rate sleep mortgage, and just the balloon payments are, I'm never getting out of sleep debt. Yeah.

0:33:31 Lindsey: They're a killer. Yep.

0:33:33 Thomas: I'm actually in sleep bankruptcy right now. Yeah.

0:33:33 Lindsey: Nope. Can't even touch the interest. Yeah. Sorry to hear that. But this measure, very brief, just a few items here. And it seems to, you know, it correlates with the MAQ, you know, and it also aligns with those more direct measures we talked about, like melatonin and like variation and temperature and things like that. Yeah, I think that according to, so what you get on the Munich questionnaire essentially is like, based on your estimated estimated preferred sleep time, you can figure out like where you are in a percentile rank compared to the population. And I calculated Z scores for you based on age and gender, because those are both

0:33:36 Thomas: Find

0:34:14 Lindsey: Big.

0:34:14 Thomas: You a podcast co-host who will calculate Z scores for you for

0:34:17 Lindsey: You're Welcome. I did this for a range of values, because I wasn't sure what you were going to say in terms of bedtime and awake time. Like, does I don't know, three or three thirty sound reasonable, like as a preferred bedtime, and then that would put you getting up three.

0:34:27 Thomas: What Think, yeah, I think three is solid. I would, I would go to bed at three. I still, still think it's mainly because the rest of society functions the different way. But like, yeah. I would be like, I don't know. I would like to go to better three and, and, you know, maybe, maybe two to three is probably like a solid range.

0:34:32 Lindsey: Yeah. Okay. Yeah. Okay, all right, so so that would put you somewhere in like the 97th or 98th percentile for your Age.

0:34:51 Thomas: What the hell?

0:34:53 Lindsey: And gender. Yeah, yeah.

0:34:54 Thomas: What are you all doing? I don't understand. I'm at a loss.

0:34:57 Lindsey: I Don't know. Yeah.

0:34:59 Thomas: I, yeah weird.

0:35:00 Lindsey: I Know. Um, And you know, even though I, I, you know, go to bed early compared to you, you know, with my my 1am-ness, more or less. I'm actually at the 95th percentile for my age and gender too, because women tend to be much earlier in their chronotypes. Yeah.

0:35:11 Thomas: Wow. Interesting. Yeah, I currently my bedtime is 1 a .m., by the way. But that's, again, to try to make try to be able to function with Arlo and with, you know, try to get some time with Lydia. And, you know, that's my compromise. Make sure I go to bed by 1 a.m. time.

0:35:20 Lindsey: A human.

0:35:29 Lindsey: Yeah, yep, I hear you. So that's some sort of background about like the distribution of chronotypes, I think that this is fun, and we're learning a lot about each other, I think this is good.

0:35:39 Thomas: I can't wait till this is viewed as some other stuff in our society is, you now, if ever, where instead of me being like, I'm sorry, sorry, I can't do breakfast with you at eight. That's insane. You're an insane person. Instead of them being like, well, you're a lazy piece of shit who doesn't do anything. I can't wait for it to be like, oh, you're just biologically or whatever the fuck, brain chemistry wise, different. And you actually have some really productive time in the late evening that I don't have. And you're just different. That would be nice. Okay, that's episode two. Sorry, episode two, yep, yep. Ooh,

0:35:54 Lindsey: Yeah, just hang on for that part two. Yeah. But yeah, totally. And that's a lovely segue, because what I want to talk about next is the factors that cause chronotypes to be earlier or later, right? And some of it is what is what you're talking about. Okay. So what affects chronotype? These factors a little bit, there's three clocks that are important to understand that sort of regulate circadian rhythms. We've got the solar clock, the biological clock, and the social clock.

0:36:23 Thomas: Yeah.

0:36:36 Thomas: And the one from Stranger Things.

0:36:37 Lindsey: And that one. That's right. So the solar...

0:36:40 Thomas: The Grandfather clock. Yeah.

0:36:42 Lindsey: The grandfather clock. That's why there's a fourth clock. But yeah. But the solar clock refers to just the 24-hour sun cycle. And so daily changes in light and temperature associated with day and night. And the solar clock is not static for most of the planet. If so, if you live at the equator, there is a stable 12-hour day-night length all year round. But the further you get away from the equator the more seasonal asymmetry there is in day-night length with days becoming longer in the summer and shorter in the winter. And this is all very important because the sun is the primary zeitgeber.

0:37:12 Thomas: Zeitgeber.

0:37:13 Lindsey: That's a fun word. Zeitgeber, that's a nice German word, means time giver. So And the sun is the primary time giver for most organisms. So in other words, the daily changes in ambient light and temperature, as it turns out, is another important time cue.

0:37:14 Thomas: Yeah. Yeah. Interesting. Interesting. Are people, are science people going to yell at us for saying the equator's, or whatever, because isn't the tilt of the earth, doesn't that make it so, not quite, it's like there's this equatorial band or whatever, that's roughly, am I nuts? It's not the exact equator doesn't give you okay all

0:37:39 Lindsey: No, I'm not that kind of scientist. I believe you. You're more of a scientist in that area than I am.

0:37:44 Thomas: We will get the emails. I'm pretty sure the equator doesn't mean you're exactly at 12 and 12.

0:37:49 Lindsey: Well, no. Yeah, okay. That, yeah, so the further away you get from the equator, The less symmetry there is. That, I think I stand by, um, yeah, so sun, primary zeitgeber, and the changes in light and temperature from the sun serve

0:37:53 Thomas: It's Yes. Yeah, yeah, yeah. Yeah, totally. I always wondered what's been gabing me, Zite. And it's nice to finally know, to put a name to a zeitgeber.

0:38:03 Lindsey: Um, Indeed it is, um, so the changes in light and, uh, temperature from the sun serve as a synchronizing cue for circadian rhythms, and that brings us to the second clock, which is the biological clock. So this refers to circadian, circadian fluctuations of all physiological processes in response to external time cues, like the sunlight and the temperature changes. And the specifics of how the circadian rhythms work in the body is actually super interesting. So the hypothalamus is this gland that regulates all these homeostatic processes like hunger and thirst and sleep and wakefulness, among other things. And there's this part of the hypothalamus that's called the suprachiasmatic nucleus, or SCN, that in mammals operates as the body's master clock. So it takes in time-relevant information from the environment, like light and temperature, and essentially orchestrates the physiological rhythms of the cells in the rest of the body. So there are nerve cells in the retina that send projections specifically into the SCN that are specifically sensitive to short wavelength light or blue light. I think people have been talking about this, right? Right? Everybody's putting blue light filters on their phones and stuff.

0:38:33 Thomas: Yeah. Oh, yeah? Yeah. Yeah.

0:39:15 Lindsey: Yeah, exactly. And that's legit, actually. So blue light is the kind that these particular nerve cells are sensitive to. They interface with the SCN and regulate circadian rhythms. Increase in blue light was associated with like, you know, morning sunlight or whatever is where we would have gotten that before screens. And so when you get that information from the retina, that there's rising blue light levels, then signal to the SCN that it's morning. Get this information. The SCN has direct connections to the retina, gets this information about the blue light, and then that changes the cycles of the cells in the SCN in a way that it can then translate into information to the cells in the rest of the body, right?

0:39:33 Thomas: Oh, oh, Crazy. Everything about the body and the brain is impossible and doesn't exist

0:40:00 Lindsey: I know. Oh, it gets better. It gets better, so this next detail is the one that's really interesting to me, so we'll see if it's actually interesting to anyone else. So virtually all cells in the body are carrying out processes that have approximately a 24 -hour rhythm, and those rhythms repeat via these feedback loops that operate very much like literal clockwork cogs.

0:40:07 Thomas: Wow

0:40:20 Lindsey: Yeah, so if you imagine a cell at quote-unquote midnight, it makes these clock proteins, so proteins whose function it is to literally keep time, and let's say that it's making these proteins until, you know, from like midnight to noon or whatever, the presence of those clock proteins then inhibits the cell from making more of those proteins, and so the production stops of the clock proteins, and then the clock proteins are just like hanging around degenerating from like noon until the next midnight. And then as the clock proteins degrade, they stop inhibiting their own production. And so the cell starts producing the clock protein again,

0:40:20 Thomas: The Yeah.

0:40:57 Thomas: Crazy.

0:40:57 Lindsey: And the cycle starts over. I know, isn't that cool? It's like it is this feedback loop. It's literally, its function is to keep time. It's to synchronize cellular rhythms across bodily systems, which is crazy. So so the cells in the SCN are on this 24 -hour cycle, right? It's regulated by the ambient light levels, and then it in turn makes adjustments to the cells in the rest of the body to synchronize them with the environmental cues, right.

0:41:21 Thomas: I have so many questions. For one, temperature, does this mean that like in different parts of the earth, this would be affected or is it just like all relative? I mean, there are places where temperature doesn't change as much at night because of humidity or whatever. There are places like a lot of places in California where it does change quite dramatically. Like it goes from like, you know, nice and warm to like freezing At night. And but is it all just, does your body just learn like what place you're in and kind of account for it or yeah.

0:41:22 Lindsey: Yeah, right, that's a really good question, and I think it has to be relative. I don't remember any of the things I was reading talking about whether it's an absolute fluid or relative thing, but I think it has to be, right?

0:41:53 Thomas: Yeah. Interesting. Then also, second question. Why haven't we easily hacked all this shit yet? Like, why isn't there like, oh, just, just, here's what you need to do to have a pill that makes you perfectly wake up and go to sleep when you want to. It's a clock pill and just fucking gives you all these pro clock proteins in the exact way you need.

0:42:00 Lindsey: Yeah, yeah.

0:42:16 Lindsey: You know, no shit. Like, I really, it doesn't seem unreasonable at all to think that there might be, like, gene therapy type things eventually that can address these things, right. I don't know.

0:42:16 Thomas: Okay.

0:42:26 Thomas: Good. Is nobody working They're all morning. People are like, we're fine with this situation. What are you talking about?

0:42:31 Lindsey: That's probably the Issue, actually. Yeah. Yeah, so that synchronization is happening daily, right? Normally, we don't really notice it because the differences in day length, if we're, you know, away from the equator, that is, the differences and day length from day to day are so small that we don't Notice that we're being constantly sort of synchronized and updated. But sometimes we do notice it. If light appears substantially sooner than it should, according to the existing 24 hour protein cycle that we're on. When that happens, the SCN sends signals to dramatically speed up or delay the cycle of protein creation and degradation in the rest of the body cells, right?

0:42:32 Thomas: Yeah. Mm hmm.

0:43:05 Thomas: So jet lag.

0:43:06 Lindsey: That's exactly it, right. So yeah, the most common time you're going to experience this is when you travel across time zones. So your cells are synced with Pacific time, you travel to the East Coast, and suddenly you're getting exposed to morning light when your cells expect it to still be dark for three more hours. And so then SCN send signals to the rest the body to adjust and synchronize cycles of all the other bodily cells, right?

0:43:08 Thomas: Yeah.

0:43:27 Thomas: Of my... OK, so this, this is why my plan ultimately won't work when I joke plans to like be a normal human was I'm just going to travel across a time zone every so often. You know, so like if I, like if I go to the East Coast, no, that's the opposite of true, right? No, yeah, if I go to Alaska, or no, more, not far enough, if I went somewhere in the West, like I don't know, Hawaii, I'm pretty much a normal person in Hawaii, but only for a little while until my clock proteins are like, "No, no, we got to make you not a normal person anymore," and so my plan is to just keep traveling, I'll get a little boat and just keep travelling West, digest as I like to become a normal person.

0:43:38 Lindsey: Yes.

0:44:10 Lindsey: That sounds really fun, actually. I'm with you. And I think that that probably is another thing that depends on chronotype, like which way it's easier for you to travel, right. But it's infinitely easier for me to travel west than east in terms of the jet lag problem. Yeah, it's the worst. Yeah, so the SCN does make these adjustments so that you can recover from jet lag, but obviously it doesn't happen instantaneously. Otherwise, jet lag wouldn't be a thing that people complained about. There are are also individual differences in how quickly people's cycles adjust. So some people recover from jet lag more quickly than other people.

That's another thing that there's an age effect for, by the way. So kids recover more quickly than adults do. That's why the SCN is the master clock, right? It's 24 -hour rhythms are sort providing the 24 - hour rhythms for the rest of the cells in their body, right. To draw a line under how cool it is that like all our cells are sort of on this clock thing, I really don't think we pay attention to this often, but it's not just alertness and tiredness that have pronounced daily rhythms, right, so immune function, digestion, Digestion, body temperature,

0:44:11 Thomas: Yeah. Mm -hmm, yeah. There'd be no lag, it would just be jet.

0:45:16 Thomas: Oh

0:45:16 Lindsey: Hormone production, like all of those follow a circadian rhythm.

0:45:16 Thomas: Yeah, yeah, so that's why travel just wrecks my digestion. It'll be, okay, so

0:45:21 Lindsey: Oh, yeah. Well, it's one of the reasons anyway.

0:45:25 Thomas: It's not just me. Yeah, it's also me just eating really badly as I'm traveling, probably. I feel

0:45:26 Lindsey: Yeah. That plus, I don't know. I think there's lots of things that make that terrible. Clench a lot.

0:45:34 Thomas: Like, okay, I, this could be tinfoil hat, but I feel like the, the pressure on the airplane, I feel like it does something to you. It just, it, it's like, one, immediately when I fly, my body is like, "Well, I guess you are never going to the bathroom again." It's forever weird.

0:45:41 Lindsey: Hmm. Interesting.

0:45:52 Thomas: Yeah, not just me. Okay.

0:45:50 Lindsey: Yep. Pretty fun. Episode two. Get all I know. No. All of these different – like literally it's almost every cell in the body that has these genes, right, mean that they're following circadian – even skin cells have clock genes and follow circadian rhythms. So yeah, so processes like water loss through the skin follow circadian rhythm. Keratin production, right? Which is involved in like the maintenance of skin and nails and wound healing. That follows a circadian rhythm. Skin blood flow. All of these things are regulated by these clock jeans, right. Right?

0:45:55 Thomas: Yeah. Wow. What? Are they using those for Okay, cool.

0:46:26 Lindsey: To keep it synced with, yeah. It's nuts. Yeah. Okay. All right. So climbing back out of the weeds for virtually all organisms on this planet, the biological clock is very tightly synchronized with the solar clock. But of course, this is less true for humans that will probably surprise no one, especially in industrialized societies, especially, especially like urban areas, right? Because many of us spend a lot of our time during the day inside buildings. And so So we're not getting as many of those cues as strongly. And we use artificial lights at night. And so for a lot of us, our biological clocks aren't strongly synchronized with the solar clock. Do see differences when you go to rural areas, though, and non -industrialized human groups. In those areas, the solar clock still has a very strong influence on the timing of circadian rhythms.

0:46:28 Thomas: Yeah. Yeah.

0:47:13 Thomas: So Do you think that, if, if I lived in ye olden times, do you think I would be more of a morning person? It seems like I would be. To me, I don't know, like,

0:47:22 Lindsey: Actually, maybe. Maybe. Yeah, at the very least, it would be, I think that you would be more tied to the solar clock.

0:47:30 Thomas: Maybe. The difference would be, yeah, less extreme or something. Like, I'd stay up until like 7 p.m. instead of 6.

0:47:34 Lindsey: Yeah, right. There does seem to be, so I read a couple of studies where they were looking at chronotypes in areas that essentially look more like that in terms of things that matter, and what they were finding was, like, yeah, I think I'm trying to remember if it was like reduced variability, because it wasn't that people slept longer, it was just that their cycles were more tied to the solar cycle, because those signals were so strong. So, yeah, if you changed your environment, you probably would change your chronotype. Yeah.

0:47:48 Thomas: Uh -huh. Yeah.

0:47:59 Thomas: I Bet, I bet. So, yeah.

0:48:06 Lindsey: But that doesn't sound that fun. You can't really podcast that well. It's harder,

0:48:10 Thomas: I don't know. I think, look, I would never voluntarily do it, voluntarily do it, but I think we would all be happier if, like, somehow technology just exploded at once, and we're like, "Well, I guess we got to live by candlelight and read books by, you know, like by the fire," and I think it would be better. Yeah.

0:48:23 Lindsey: You're not wrong. It doesn't sound terrible

0:48:26 Thomas: It would be better, But I don't want to do it. I would never.

0:48:26 Lindsey: To me. Yeah. Yeah, that's our solar and biological clocks. I've got one more clock to tell you about. And that's the social clock. So that refers to, yeah, that to cues that synchronize our activities with other people, right? So there's all kinds of things that are essentially just operations to synchronize human activities with each other?

0:48:37 Thomas: Social clock, okay, uh, So When Heath, Noah, and I get together, it's over. We're just fucking. It's, we never would sleep

0:48:51 Lindsey: Yes. Never. Never again, right? That's why it's so fun. Yeah, so things like time zones, you know, work timing, social activities, daylight savings time, I think would fall into this category. Like all of those things are social time cues. Those are just sort of social regulation mechanisms. Historically, the social clock, just like the biological clock, was heavily regulated by the solar clock. People timed activities according to, you know. The solar cycles. But again, with the introduction of artificial light, and honestly, clocks themselves, right? Social and solar time had the opportunity to become much less in sync.

If I can tell you I need to meet you when your clock says 12 instead of at high noon, right, that means that we have this opportunity to dissociate those clocks. So clock and biological clock and social clocks, they all regulate the timing of our sleep -wake cycles on a day-to-day basis. And one takeaway from this stuff should be that environmental factors can be thought of as one important set of causes of chronotype, right? So day length across the year, right, know, for people, again, not the further away you live from the equator, right. The more your chronotype is going to change as with the seasons, essentially, because of those changes

0:48:53 Thomas: Okay. Hmm. Yeah. True. Yeah.

0:50:04 Lindsey: In solar cues, especially if you're living in a rural area, or speaking of that, rural versus urban environments. So people who live in urban areas have chronotypes that are, on average, later than people living in rural areas. And this is thought to be because people in rural áreas have their biological more tied to the solar clock, because of more time I'm outdoors, and things like that.

0:50:22 Thomas: Plus the social component that you just talked about, maybe more to do, get together, hang out, and then we all start staying up late, and then they're like, "Well, everybody else is doing it."

0:50:24 Lindsey: Yeah, absolutely. Yeah. Yeah. And so that would be the, the other factor to mention there. So social factors as well, work schedules, cultural expectations for timing of work and recreation, all of those things are going to have an influence on, on when people prefer to wake up and go to bed. Right? So those are influences on chronotype. It's reasonable to, to call them that way. But I know that this isn't really what you want to know when you ask what causes chronotype differences.

0:50:53 Lindsey: What I think you really want to Know is why some of us respond differently to the same external time queues. Why do some of Us want to play code names until 3am and other other people just

0:50:53 Thomas: Mm -hmm. Yeah. Right. And Arlo wants to shit his pants at 5 a.m.

0:51:04 Lindsey: Exactly. Right. Yet, so there are a number of causes that have been identified that can speak to those individual differences. So there is a pretty strong evidence that differences in chronotype type are strongly heritable. So,

0:51:17 Thomas: Yeah. Well, okay, let me give you my armchair evolutionary biologist theory. As this, as a population, wouldn't you want to have, like, where just for survival of everybody, when you want to have some people are like, "Yeah, I stay, I'll do the night watch, no problem, that's great for me," and other people are like, "I don't want to do that, I'll be up early in the morning."

0:51:36 Lindsey: I think I've heard that suggestion before in a paper, actually. I'm not, it doesn't seem insane. It's possible that there's sort of a pressure for variability, I guess.

0:51:39 Thomas: Doesn't seem insane. Yeah.

0:51:46 Lindsey: That could very well be the case.

0:51:48 Thomas: You didn't come across that.

0:51:49 Lindsey: Not in this round. I, you know, I was focusing more on these mechanisms than some of the functional accounts, I guess. Yeah, I think that a lot of the functional accounts that I have seen, so I looked at some about like explanations for age and gender differences, they're still pretty speculative. So I don't know that there's been good enough work yet to identify like functional mechanisms for variability in humans. There certainly are in some species. Is pretty strong evidence that like, yeah, yeah, the differences in chronotype are strongly heritable.

So family studies suggest that chronotype is up to 50 % heritable, meaning that up to half of the variability in chronotype may be due to genetic differences, which is, that's a pretty strong sort there. And recent work has identified several gene candidates that might contribute to differences in chronotypes through different mechanisms. So like we talked about the fact that the circadian cycle of protein creation and degradation that keeps cells for all the, or keeps time for all the bodily cells, there are genes that regulate the speed at which that cycle happens for the clock cells in the SCN, which then functionally translate into how long your cell's circadian rhythm would be if you weren't synchronizing with external time cues.

0:51:51 Thomas: Oh, huh. Okay.

0:52:59 Lindsey: Yeah. So if you like locked people in a windowless room and then just saw what their activity patterns looked like, right, these genes are regulating like how long that cycle would be. Most people, if you lock them in a room, they actually do default to a cycle length that's about 24 hours. It's just a few minutes longer than that. But there is individual differences in that that seem to be heritable. So some people...

0:53:20 Thomas: So wait, does that mean that you like if you were in a windowless room for one, I think you just die. But like if You're in a windows room forever, would average, do you eventually just like get way off of what like you start? Let's say you start with what what day and night is on the surface of the earth and then you're in a place, would you just get way off eventually? Like you might be totally like nocturnal just because each day you're adding a minute or something.

0:53:26 Lindsey: Well, yeah, that'd be creepy.

0:53:47 Thomas: Wow. That's really interesting, which is, that's weird because I'm pretty sure back to the astronomy part of the science, I thought a day is actually slightly less than 24 hours because of the, around the the sun. There's is it? Sidereal day or whatever.

0:53:46 Lindsey: Yeah, yeah. Actually, yeah It is. It is very interesting, because I think the average is like, is hours, and yeah, it's like five minutes or something yeah

0:54:08 Thomas: No, it's not your science. I'm pretty sure that due to the earth going around the son as well as, you it's spinning as not, you know, it's not exactly 24 hours. It is 24 minus a little bit.

0:54:08 Lindsey: Not my science I believe you, um, the thing is, is that when is, you think about how these mechanisms evolve, right? Not necessarily evolving in response to the precise length of the of the day, right, because it's it's dependent on these kind of, um, proxy cues, right? So if, if you've got a mechanism that works really well when it's regulated through exposure to light and temperature, which over evolutionary time it was, right. Then just having that, um, mechanism to sort of synchronize in that way is, it's probably more fresh. And then, and then also when you think about the fact that like, um, depending on where you are on the earth's crust relative to the equator, right, that, that those cycles are going to change.

0:54:35 Thomas: Yeah.

0:54:58 Thomas: A good point. It isn't as though like, again, I don't even think there is one place due to the tilt of the earth that the day is exactly the same throughout the whole year.

0:55:06 Lindsey: You Right. So it makes, it makes sense that this is designed as sort of a flexible mechanism that's inherently sort of embedded in context, I guess.

0:55:13 Thomas: Okay. Remind me, I think I just don't, don't think I ever got any sort of genetics in my high school science, a terrible high school science except physics. Remine me, because I'm, in my family, it's the women are all morning people and the men are all night people. When you say it's 50 % hair, like, what does that mean? I don't understand. Does that mean that, like on average, what the hell does that mea? Should families all be the same chronotype or no?

0:55:27 Lindsey: No, Yeah, it's like, so, so if, if somebody says that something is 50% heritable, that means that if you, if you look at differences between two people, you can attribute up to 50% of that to differences is in genetics, and then up to 50 of that to differences in environment, so you, you wouldn't necessarily expect you'd expect chronotypes and families to be correlated more than like with the general population, um, you wouldn't expect everybody in the same family to have the same chronotype.

0:56:08 Thomas: Well, Okay, so you wouldn't expect like whole families to be the same chronotype?

0:56:11 Lindsey: That would be unusual, I think, yeah.

0:56:12 Thomas: Yeah. Gotcha. Hmm.

0:56:13 Lindsey: Especially since it's regulated by lots of, this is not a single gene trait. So this thing we're talking about with cycle length, that's one thing that's associated with chronotype is just how long your sort of free cycling rhythm is. that'S one thing it's been associated, but there are other mechanisms too that are also heritable and influence it through other mechanisms. For example, there's a gene that's involved in regulating orexin receptors. So orexin is a neuropeptide that's involved in regulating wakefulness and alertness, among other things. Like narcolepsy is often caused by deficient orexin production. And so genes that regulate receptors for orexin may also contribute to individual differences in chronotype. So that's another gene.

0:56:19 Thomas: Okay.

0:56:54 Thomas: I really thought you said erection production, but I'm gonna not, okay. I

0:56:57 Lindsey: That has been strongly implicated as well in sleep -wake time, for sure. It's not not implicated. Yeah. It

0:57:01 Thomas: Mean, with the timing of morning wood is a real, okay, that might be part of it. Might be part of the

0:57:10 Lindsey: Is. I actually did run across that in my reading. Yeah. About testosterone levels. And I don't know. It's fun stuff.

0:57:11 Thomas: Yeah that would be like the shortcut of the chronotype test. It's just like we're gonna time your boner, and if it comes up at this time in the morning, you're a night person.

0:57:26 Lindsey: Yes. Yep. So one other one other genetic contributor that I think is interesting. Are heritable genetic differences in sensitivity to zeitgeibers. So like light cubes, or light cubes. You know, again, right, right? Our cells. Oh, yeah. It's like gabers. I always say zeitgeber.

0:57:43 Thomas: I've always been so sensitive to zeitgebers. It's a, that's something everybody's always said, and it's weird that I finally know why. Look over there, zeitgeber, oh shit, what, oh yeah zeitgebr

0:57:51 Lindsey: It Yeah, it's just your genes. That's all it is. It zeitgeiber. I say zeit geiber because of zeitgeist. So I want to say those the same, but it's like geiber. Yeah. My bad. Yeah Yeah. Anyway, so all our cells. Right. We've got these these internal clocks. You know, they're they're their internal clock thing. They've done experiments where they keep subjects in these windowless rooms and make them go crazy. They keep constant light conditions in these particular experiments. And then periodically, they'll expose subjects to a pulse of bright light. And in general, what they show when they do that is that the light pulses act to sink the subject's biological clocks, just like exposure to sunlight would. And that makes sense, right?

The interesting thing is that The extent to which a pulse of light causes a change in the biological clock, so causes it to speed up or slow down, depends on when during the biological cycle the pulse is presented. So if you're, again, you're in a windowless room, you don't know where the sun is, constant light conditions, but if your cells are in the phase of their cycle associated with noon and you administer that light pulse, the cycle doesn't change, right? If your cells are in the phase of their cycle associated with 10 p.m. or 2 a.m., and you administer that light pulse, then that light pulse has a much larger effect on the cycle. So it, you know, it

0:58:01 Thomas: Yeah Yeah, mm. -hmm, yeah, right, yeah.

0:59:03 Lindsey: Brings it forward or backward.

0:59:03 Thomas: It's like, ah, what happened to the sun? Okay, crap, reconfigure.

0:59:06 Lindsey: Exactly. Yeah. So there's variability across the 24 hour cycle in terms of how responsive our biological clocks are to light cues. To bring it back to genetic differences, there's evidence for heritable differences in how responsive different organisms are to late exposure at different points, right? Some people show much more dramatic suppression of melatonin in response to light exposure than others do, which has direct consequences for shifts in circadian rhythm. So, you know, if you get a huge circadian suppression in response to light, right, that means that your cells are going to respond much more strongly and your phase is going to shift much more than somebody who doesn't respond as much.

0:59:41 Thomas: So does that mean you'd be an easier traveler, like you'd have less jet lag because you get to the new time zone, you're like, oh, okay, right.

0:59:47 Lindsey: Yeah, that's exactly right. That means that your cycle would shift more rapidly than somebody who has less sensitivity to that, right? And so that's right.

0:59:54 Thomas: Okay, Well, I actually wasn't sure if the cycle shifting rapidly was like better or worse for jet lag. You know, like I wasn't sure. I guess that means you adapt faster, but like that period of time where you're just like, "Oh, I'm freaking exhausted and I can't do anything," is... guess I wasn't sure if that would be better or worse, or if that's a different thing entirely. Okay.

1:00:13 Lindsey: No, no, I think that, yeah, so that if you're shifting quickly, that means that your rhythms are shifting more quickly to be in time with your new time zone. So that would be a good thing, I would think, subjectively, right.

1:00:22 Thomas: Gotcha. Yeah. Yeah.

1:00:26 Lindsey: Just to sum that up, right, there's lots of lots of interesting heritable differences here in terms of how we respond to these different cues that regulate our circadian rhythms. It can make it easier or harder for us to adjust our rhythms, right? And that's going to contribute to chronotype, right. So definitely genetic basis, definitely it's not true that we all start out the same and we just need to be less lazy if we want to get up earlier, for sure.

1:00:39 Thomas: -hmm. God. Damn right.

1:00:47 Lindsey: Yeah, right, couple of other interesting things to talk about here in terms of individual differences. So there's a really interesting developmental component to a chronotype that we sort of previewed earlier. Age and chronotype are pretty strongly associated with one another. And you didn't need me to tell you that because of your kids.

1:01:04 Thomas: Yeah, but I don't know which way it goes, because I know like the old, the most old people, it, like, fucking, well, they also don't require as much sleep. I don't know if that's part of it too.

1:01:13 Lindsey: Of those things, all of those thinks. Yeah. So there's a curvilinear relationship between age and chronotypes. So young kids have earlier chronotypes and then at puberty, the average chronotype like gets a lot more toward evening, right? Yeah. Right. Yeah. So childhood through puberty, average chronotype, very, very early. It's something like, so there was one study of toddlers like two to three years old, and it indicated that about 60 % of two to 3 -year -olds are either definite or moderate morning types. And contrast that with adults, it's like between 16 % and 37%, depending on the sample.

1:01:15 Thomas: Okay. God, okay. Right. But once again, normie is extreme morning type relative to me, for my But okay. Yeah, sure, so

1:01:54 Lindsey: Yeah, right. Right. Yes. But yeah, so young kids, early, types. And then with the onset of puberty, kids rapidly become more and more evening inclined until around age 20. And this is on average like peak eveningness age. So people are like the most evening inclined that they're ever going to be in their lives around age twenty. Yeah.

1:02:14 Thomas: Really, it's true that like you could be more of a party person, you know, in college, even if you are in morning person, then, like, later on in life you're like, "I just can't do it anymore," whereas I'm like, "No, let's still stay up all night."

1:02:18 Lindsey: Yeah, no, no. No, that's that's exactly right. Yeah so So peaks around age 20 and then you see reversal and people start to gradually become more morning inclined through early, middle, and then later adulthood. And older adults, as you noticed, have even earlier chronotypes than young kids. But you're right that the difference is that older adults sleep less. But even with that, they are more morning -inclined in terms of, like, the middle of their sleep cycle than young children. Once they get up to, I think it's, like around age 60 that they pass kids in terms being more morning inclined. And in terms of why that happens across the lifespan, there's a lot of work suggesting that various mechanisms that regulate circadian rhythms just get shittier

1:02:30 Thomas: Interesting.

1:02:51 Thomas: Yeah.

1:03:04 Thomas: Along

1:03:04 Lindsey: As we age. So the SCN becomes, exactly, right? Just everything sucks once you, yeah. So, the SCM gets worse at regulating circadian rhythm. We secrete less melatonin, which is important for regulating that. And there's other things as well. So it's just, yeah, we get shitter as we age. But it also seems like there's something unique about the shift toward eveningness around puberty, right?

1:03:07 Thomas: With everything else, huh?

1:03:27 Thomas: Yeah.

1:03:27 Lindsey: And we were kind of talking about this earlier, you know, I think that conventional wisdom at one point was just that like, well, adolescents are really becoming interested in like peer interaction and stuff like that. And so they want to spend their time doing things other than sleeping, so they wanna stay up late. But there's very good evidence at this point that there are really predictable physiological shifts in circadian regulation that are triggered by the onset of puberty, and they're mediated by sex hormones. Turns out that circadian rhythms are very sensitive to sex hormone levels, which is interesting. And I think I mentioned before that this shift is not unique to humans. You see it in other mammals as well. You know, unless rhesus monkeys are also just becoming hooligans and getting up to, yeah, it's not a thing.

1:04:06 Thomas: So Wait, I get, I do want to clarify, then. I always thought, and again, this is another variable, is the how much sleep you need. I always assumed the teenage adolescent, whatever, was just, you know, you just need more sleep for development and stuff, and that's why you want to sleep later. But it's not, so much that interesting.

1:04:22 Lindsey: Well, I mean, no, no, actually it's not, I don't, I don't think that the, yeah so what happens with the amount of sleep is that that that actually pretty steadily declines from like infancy through childhood and adolescence and so on it's

1:04:27 Thomas: Yeah. I can't wait, wait for that to happen. I guess I'm still in infancy then. Can't wait for the, I'm looking forward to that someday.

1:04:39 Lindsey: That's a, that's another individual difference, right? Like, I, yeah, I think I'm higher, higher on that too. Like,

1:04:44 Thomas: I need a good 15 hours a day.

1:04:46 Lindsey: Yeah. Right. No, but yeah, like infant sleep the most and then childhood, it declines a little bit. Adolescence is a littlebit lower and then it declimes through adulthood. So that's pretty, pretty linear, I think, or at least it's in one direction. But no, the shift in puberty is very much just about the timing of sleep, which is, it is pretty interesting.

And so, yeah, so there's a couple of studies and I, you know, I've seen these criticized, so it's, I don't think this is a consensus position or whatever. But there's a couple of studies that seem to suggest that one of the mechanisms that might regulate the change around puberty is that the sensitivity to morning versus evening light might shift, which is kind of interesting.

So that adolescents or like around the time of puberty, they're becoming more sensitive to evening light in terms of how that affects their cellular circadian rhythms and less sensitive to morning light, and that, that, that might be responsible. So again, I don't think that that's like a firmly established finding, but it seemed interesting and I wanted to mention it. So that's age effects. I also mentioned that there's some pretty large and stable gender -related differences in chronotype, which, you know, it is.

1:05:54 Thomas: That's interesting.

1:05:56 Lindsey: It's unsurprising when you know that circadian rhythms are sensitive to sex hormone levels, right? So that, you now, at least in a descriptive sense, that kind of fits. I get the sense that there's a great account functionally of why women and men would be different. So the difference is that men tend to have later chronotypes than women. Look at the, there's like lifespan graphs that show this, like before puberty, there was no difference as a function of gender. And then there's a gap from puberty to early adulthood that gets larger and larger. And And then after early adulthood, it shrinks again. And then by about age 50 or so, there's no difference again. But in like, yeah, yeah. Yeah, from like 20 to 50, you get this pretty stable difference with men sort of becoming more evening inclined.

1:06:34 Thomas: Really? Oh, it would hard to imagine that not being related to like child rearing or bearing given that it's like that exact age.

1:06:48 Lindsey: You know, I had that thought too that it might be a parenting-related adaptation. But from what I've read, it doesn't – the effects don't really seem to line up with that very well.

1:06:53 Thomas: Yeah. Really. I would have thought it'd be like, I don't know, a long, long, I mean, just, just having gone through having kids. And again, we're obviously always talking about population averages and stuff, it's not like this applies to everybody, but yeah, it's like if you're just like a breastfeeding, you parenting couple, whatever, it's like the the baby wakes up and the mom breastfeeds and, you know, like there's not a whole lot, I can, especially, especially pre like bottle and formula technology, like what am I doing, you know, I maybe I'm staying up late, uh, out for the saber-toothed tigers, I have no idea, but I don't know if it's the

1:06:59 Lindsey: Yeah. Yeah. Yeah. I mean, I saw couple of accounts that were trying to explain this functionally. None of these are consensus positions. These all seem to be speculative at this point. One paper I was reading by an animal behavior guy seemed to think that it could be a sexual selection effect, effect so that that, and this is, this is true in like some other species, there's like a species of birds where, um, males have on average earlier chronotypes, and that's thought to be a sexual selection effect, like they're getting access to more mating opportunities because they're waking up earlier.

1:07:36 Thomas: Early

1:08:01 Lindsey: Yeah, gets the uh something indeed.

1:08:00 Thomas: Bird Gets to Use his worm. Yeah,

1:08:04 Lindsey: Yeah. So some people have argued that there might be sort of a analogous thing that happened with humans for or late chronotypes. I'm not particularly persuaded by that, but we'll talk about a paper next time that speaks to that.

1:08:17 Thomas: That's interesting. It is always important to remember. And how you evolutionary psychologists that come up with all these these things that we've kind of, you've debunked on the show a lot, I always forget that it's not, not everything has to be like, oh, that's an adaptation that serves this function. It could also be a sex selection thing, that's like just so happened that like this was selected for, for like mating preference reasons, and not like, oh, I need to be such and such so that I can wrestle an alligator, or whatever, you know, like that kind of thing.

1:08:34 Lindsey: Yeah. Right. Yeah, that's a good point. Yeah because it would still be an adaptation. It just wouldn't be an adaption to promote survival. Yeah and it could also be a byproduct. Like it's possible that this just can't, you know, I don't know. It's but there, Yeah, yeah, that happens. So we're going to talk about one paper next, next time that that's kind of, uh, taps into this a little bit, so maybe we can, we can come back to that one, but right, so one just last brief thing, since we're, we're short on time here, um, is a cool one, I'd never heard of this, but it looks like there's, it's possible that there's an effect of the day length when you were born on your eventual chronotype. Yeah.

1:08:50 Thomas: Right. Right. Right. I feel like there's a ton of those in science. It's just like, yeah, no, just accidental. Cool.

1:09:25 Thomas: Interesting. So you're born dead of winter versus summer and depending where you are on the planet kind

1:09:28 Lindsey: That's right, that's. Yeah. So some studies have found that the incidence of moderate and extreme morningness is higher among people who were born during shorter day lengths. And absolutely right to say all of those things in it. So they don't just look at your birth date. They look at the birth date and the latitude of the place that you were born. And use that to calculate what the day length was.

1:09:32 Thomas: Yeah. Right. Boy, people born in like Northern Alaska just fucking forget about it. What are they doing? How do they even?

1:09:56 Lindsey: Oh, I know. Yeah, they don't. They

1:09:59 Thomas: Yeah.

1:09:59 Lindsey: Don't, yeah. Yeah. Yeah. So it's a more morningness if you're born with a shorter day length and then more eveningness incidents for people that are born in the summer, which I think fits with you, right? There you go.

1:10:09 Thomas: I was born in the summer. I think July 30th is my my birthday. When's the longest day? Well, I guess it depends where you are.

1:10:13 Lindsey: Yeah. It's June, middle of June, I

1:10:18 Thomas: Middle Middle of June. So, okay. Fit with little Arlo man though, because he's April 15th. Okay. Not But who knows? There's lots of factors. Yeah.

1:10:18 Lindsey: Think, think. Um, But It's What? Yeah. It's one factor, and this tends to be a small effect. Um, studies that have found the effect the most strongly are in fact like, uh, places where the day length changes are like super extreme. Um, so at higher latitudes, they find this more strongly, but I just, I thought that was really cool, like yeah, um, so That was, that was fascinating. I never heard of that before, and there's... there's some debate over whether that's a function of like the day, the light itself, or whether it's a temperature function, which would be kind of interesting.

1:10:37 Thomas: That makes sense. Yeah, that is cool. Cool.

1:10:52 Lindsey: Anyway, that's pretty cool. Okay, so closing thoughts, closing thoughts. So chronotype, it's dynamic, right, in the sense that it does change according to all of these environmental cues, solar clocks, social clock, all that kind of stuff. But there definitely are these trait -like individual differences that interact with those environmental factors. I was trying to be careful throughout this discussion not to refer to chronotype is like when you would like, quote unquote, naturally wake up, because that implies that everybody has sort of like a single ideal sleep cycle independent of context. And given how circadian rhythms are regulated, that it's inherently embedded in context.

1:10:52 Thomas: Good point.

1:11:22 Thomas: Right. Right,

1:11:27 Lindsey: So that wouldn't really make sense.

1:11:28 Thomas: So like if you move somewhere else or if you, yeah, like you could, I could be a night person, but, well, okay, do you think I could really be anything other than a night person anywhere on the planet? Like, honestly, is there that much of a difference?

1:11:30 Lindsey: Yeah.

1:11:40 Lindsey: Well, you I mean, look, technically, I think that you could construct an environment for yourself where you could be on whatever sleep cycle you wanted. But it would be so onerous to do that because you can't control, you can control the environment outside of your house in terms of exposure to different kinds of signals and stuff. Right. I think that like, I don't know, there is, so

1:12:00 Thomas: I'm not even understanding the hypothetical way that I could do this.

1:12:03 Lindsey: You could, if you built yourself a windowless room, you could you could yeah, you could create artificial cues so that you could wake up at whatever objective time you want to wake up. Like, right.

1:12:08 Thomas: Well, okay. Sure. Yeah. Okay. You're right. Right. Yeah, I could. And if I change the rotation of the earth, I could also do. Yeah. I wasn't really counting that. Sorry. I meant like a realistic thing. Yeah

1:12:23 Lindsey: Yeah. Yeah. No, I mean, I think that the best you can probably do in terms of like a realistic strategy is trying to control the environment in which you sleep. I don't know about you, but like, I really like having blackout shades.

1:12:36 Thomas: I know I had, I had more blackout shades at the old house, but these ones are terrible. I gotta, I gotta fix that. But on the other hand, what I really need, and I think they have this is like, I need ones that like then open in the morning automatically.

1:12:41 Lindsey: That's a bummer. Yeah. Yeah, Right.

1:12:48 Thomas: Right. Cause I need it to be light in the morning and just no light at night to try to actually go to sleep.

1:12:48 Lindsey: Yes. Yep. That is exactly what you need. You need to be...

1:12:55 Thomas: Okay. Here's what I want to know for next episode. We're so out of time. I've seen so many different things about melatonin and like taking melatonin and all that. And if that's a good idea, bad idea, poison your kid to death with it idea. I know you're not a doctor, but I'd be curious if that has come up in your research and if you could answer every every question everyone has about that.

1:12:55 Lindsey: Yeah. Yeah. Yeah. Hmm.

1:13:16 Lindsey: Yeah, yeah. No, I know a little bit about it. So I'll double check my intuitive answer. And yeah, we can follow up on that. That's cool. Yeah so next time next time we're gonna talk about chronotype chauvinism.

1:13:19 Thomas: Okay. Next time we rage about society.

1:13:29 Lindsey: Yeah yeah. Evening orientated? Are they more likely to be psychopaths? That's that's what we're going to be tackling. Yeah that's one of the papers. Yeah probably

1:13:33 Thomas: Ooh, I forgot about that, yeah, yeah. I forgot about that that's probably true.

1:13:40 Thomas: We'll find out. I don't know extreme morning people seem psychopathic to me. Oh yeah, I go to bed at 6 and I wake up at 3 a.m. and I start fucking gardening or something. Like, what are you talking about? Yeah, that should be definitionally psychopathic behavior, but maybe it's not.

1:13:40 Lindsey: So. Yeah no. Terrible. It's the worst. Yeah yeah you're not wrong yeah

1:13:59 Thomas: All right. This was delightful. I'm going to go to sleep. No, I'm going to stay up all night and then go to bed. Tune in for episode two, everybody. You then.

1:14:01 Lindsey: Same yeah that

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