WEBVTT - When the Sun Doesn’t Sleep 0:00:10.960 --> 0:00:13.520 When you go to a friend's for dinner and you 0:00:13.600 --> 0:00:16.479 get talking, or you go out on the land on 0:00:16.600 --> 0:00:19.800 a boat, or go outside anywhere on a walk and 0:00:19.920 --> 0:00:22.279 you just kind of relaxing and chilling out, and then 0:00:22.520 --> 0:00:24.079 you get back into the house. 0:00:23.920 --> 0:00:27.480 And look at a clock. You're like, oh god, it 0:00:27.560 --> 0:00:28.800 was like five hours late. 0:00:28.840 --> 0:00:30.800 And then I thought it was because the sun did 0:00:30.800 --> 0:00:33.279 not go down, and I did not realize because my 0:00:33.280 --> 0:00:36.280 brain didn't tell me that that wasn't normal. 0:00:38.600 --> 0:00:40.720 When most of us say on top of the world, 0:00:41.159 --> 0:00:44.440 we usually mean it metaphorically, as in being in a 0:00:44.479 --> 0:00:48.000 good mood or in a good place. But for Addie Scott, 0:00:48.440 --> 0:00:51.080 top of the world is a very real location that 0:00:51.120 --> 0:00:51.920 she calls home. 0:00:53.080 --> 0:00:55.520 You think of like Canada and North America on a 0:00:55.560 --> 0:00:59.600 map and go as far north as you can and 0:01:00.200 --> 0:01:03.920 west without getting into Alaska, and you find Anyuvik. 0:01:05.080 --> 0:01:08.720 Addie is a coordinator for Community Greenhouse in Innovook, Canada, 0:01:09.040 --> 0:01:12.120 a city located in the Arctic Circle. Because of its 0:01:12.200 --> 0:01:15.760 extreme north location and the tilt of our planet's axis, 0:01:16.160 --> 0:01:20.160 people who live there experience fifty six days of continuous 0:01:20.200 --> 0:01:23.880 sunlight every summer and about thirty days of polar night 0:01:23.959 --> 0:01:24.440 in the winter. 0:01:25.680 --> 0:01:28.920 So in the summer, I usually just like make sure 0:01:29.280 --> 0:01:30.920 that I try not to. 0:01:30.880 --> 0:01:33.320 Go outside past like eleven PM. 0:01:33.040 --> 0:01:35.840 And if I do, I get very confused and my 0:01:35.880 --> 0:01:37.720 brain's like, Kate, it's time to go to work. 0:01:37.720 --> 0:01:38.520 Now it's the morning. 0:01:39.720 --> 0:01:42.119 But it's great for waking up in the morning because 0:01:42.440 --> 0:01:44.560 it's just bright all the time, and in the winter 0:01:44.880 --> 0:01:46.200 mad it's hot to care a bit. 0:01:48.320 --> 0:01:51.560 In most inhabited places on the planet, we can rely 0:01:51.640 --> 0:01:53.840 on signals from the sun to let us know when 0:01:53.880 --> 0:01:55.880 it's time to go about certain parts of our day. 0:01:56.640 --> 0:02:00.840 So for Addie, who moved to Nuvik from Yorkshire, United Kingdom, 0:02:01.160 --> 0:02:04.560 the endless days and continuous nights were something she had 0:02:04.560 --> 0:02:05.200 to get used to. 0:02:05.840 --> 0:02:09.600 It's honestly, like I mean, it sounds like a cliche. 0:02:09.680 --> 0:02:12.240 It's nothing I've ever experienced before, and it's nothing I 0:02:12.240 --> 0:02:13.760 could have imagined before. 0:02:14.919 --> 0:02:18.000 It's a very unique thing that few humans will ever 0:02:18.080 --> 0:02:21.760 witness in their lives, and while whole populations have learned 0:02:21.760 --> 0:02:24.600 to thrive in this environment, it still comes with its 0:02:24.639 --> 0:02:27.720 own set of challenges. I also sat down with doctor 0:02:27.760 --> 0:02:32.200 Stephen Lockley, a neuroscientist an Associate professor of medicine at 0:02:32.200 --> 0:02:36.760 Harvard University to talk about what these unique and extreme 0:02:36.919 --> 0:02:39.880 day and night periods due to our minds, our bodies, 0:02:40.080 --> 0:02:41.280 and of course are sleep. 0:02:42.400 --> 0:02:46.080 We've not evolved as humans to live in constant darkness 0:02:46.160 --> 0:02:49.160 or constant light. We can override it with the use 0:02:49.160 --> 0:02:52.680 of electric light or light avoidance in the summer, but 0:02:52.800 --> 0:02:56.200 clearly there are still some anger effects of the light environment. 0:02:56.560 --> 0:02:59.640 It's not exactly the same as living further south, and 0:02:59.720 --> 0:03:02.120 so yes, we do find the further north you go 0:03:02.639 --> 0:03:04.040 there is a bigger risk to health. 0:03:05.160 --> 0:03:08.320 Despite the risk, people have figured out how to adapt, 0:03:08.680 --> 0:03:11.679 with evidence showing that humans may have first migrated deep 0:03:11.720 --> 0:03:15.240 into the northern hemisphere as far back as thirty thousand 0:03:15.280 --> 0:03:18.720 years ago. Today, we're going to look at what sleep 0:03:18.800 --> 0:03:21.359 is like in the Arctic Circle, a place with light 0:03:21.440 --> 0:03:24.240 and dark cycles that seem alien to the rest of 0:03:24.240 --> 0:03:27.920 the world and where the adaptability of its residents is 0:03:27.960 --> 0:03:31.799 a testament to the ingenuity of the human race. On 0:03:31.840 --> 0:03:41.760 this episode of Chasing Sleep, when the Sun doesn't sleep. Hi, 0:03:42.280 --> 0:03:46.640 I'm Anahad O'Connor, and this is Chasing Sleep and iHeartRadio 0:03:46.680 --> 0:04:00.000 production and partnership with Mattress Firm located two thousand miles 0:04:00.160 --> 0:04:03.160 north of Seattle, and with only one road connecting it 0:04:03.240 --> 0:04:06.480 to the rest of the globe. Nuvik, Canada is one 0:04:06.480 --> 0:04:10.720 of the most remote yet interesting places on Earth. Most 0:04:10.760 --> 0:04:13.600 of the Arctic Circle is so extreme that, despite some 0:04:13.680 --> 0:04:17.000 modern settlements, a lot of the land remains completely untouched. 0:04:17.600 --> 0:04:20.840 The wildlife found here is some of the most unique. 0:04:21.000 --> 0:04:24.599 The forests are dense and lush, the waters are clear 0:04:24.680 --> 0:04:28.479 and blue, the day lasts an entire season, and the 0:04:28.600 --> 0:04:31.680 nights are illuminated by the amazing northern lights. 0:04:32.880 --> 0:04:36.800 It's basically like real life Nannia is the best way 0:04:36.880 --> 0:04:37.720 to describe it. 0:04:38.279 --> 0:04:38.960 So after I. 0:04:39.040 --> 0:04:42.400 Finished my masts, I didn't know where to go, so 0:04:42.440 --> 0:04:45.960 I threw a dot at a map and this was 0:04:45.960 --> 0:04:47.280 the closest place it landed. 0:04:48.000 --> 0:04:50.160 So here I am doing the things. 0:04:51.200 --> 0:04:54.200 Wow, So you really did that and decided, Okay, that's 0:04:54.480 --> 0:04:58.240 where I'm headed, And how did you figure out how 0:04:58.279 --> 0:05:01.600 you were going to get there and prepare for it 0:05:01.760 --> 0:05:03.240 and make a life there. 0:05:03.960 --> 0:05:06.719 I actually just kind of zoomed in on Google Maps 0:05:06.720 --> 0:05:10.479 and was like, wow, there's like really nothing there, and 0:05:10.520 --> 0:05:12.680 then kind of zoomed in a little bit closer and 0:05:12.720 --> 0:05:15.200 then found the names of the towns like surrounding it, 0:05:15.360 --> 0:05:19.080 and then just looked for like volunteering and job opportunities 0:05:19.120 --> 0:05:22.719 to travel and then found a place working with sled 0:05:22.760 --> 0:05:27.680 dogs and working with them and email called them was like. 0:05:27.640 --> 0:05:30.960 Hey, do you guys have sled dog training jobs? Is 0:05:31.000 --> 0:05:31.440 that a thing? 0:05:31.800 --> 0:05:33.520 And they said yeah, And I worked for them for 0:05:33.760 --> 0:05:36.160 like eight months, left on a road trip, and then 0:05:36.279 --> 0:05:37.479 got a job at the Greenhouse. 0:05:38.560 --> 0:05:40.960 So while it must be pretty amazing to be surrounded 0:05:40.960 --> 0:05:44.520 by so much beauty, how do you handle the unique 0:05:44.560 --> 0:05:47.320 times of total light and dark that come with living 0:05:47.360 --> 0:05:48.040 in Annivik. 0:05:48.800 --> 0:05:51.479 It's kind of amazing really, Like in the summer, it 0:05:51.839 --> 0:05:57.440 happens so fast that you go from darkness to like 0:05:57.560 --> 0:06:02.360 twenty four hour daylight basically. So I know, officially it's 0:06:02.760 --> 0:06:05.599 twenty four hour daylight for one month, but the sun, 0:06:06.080 --> 0:06:09.000 even though it sets a little bit, is still light 0:06:09.120 --> 0:06:10.839 for like three months either side of that. 0:06:11.160 --> 0:06:12.719 It's really really cool. 0:06:12.800 --> 0:06:15.040 And I don't know, you have no idea what time 0:06:15.080 --> 0:06:16.760 it is any time of day, and if you're really 0:06:16.760 --> 0:06:19.120 bad at wearing a watchhalk keeping your phone on you 0:06:19.160 --> 0:06:21.919 like I am, you're just like Beth but wondering the 0:06:21.960 --> 0:06:24.600 whole time. You have no idea what time is going 0:06:24.640 --> 0:06:26.359 for a walk with the dog. I'll hanging out with 0:06:26.360 --> 0:06:28.320 some friends and you'll look outside and be like it's 0:06:28.320 --> 0:06:30.560 still light. Maybe it's ten pm. Maybe I'll go to 0:06:30.600 --> 0:06:33.680 bed it's like five am, and uh, they're like, oh, 0:06:33.720 --> 0:06:34.479 it's the next day. 0:06:34.839 --> 0:06:35.239 Oops. 0:06:36.400 --> 0:06:39.320 So that's constant daylight and then the opposite happens in 0:06:39.360 --> 0:06:39.760 the winter. 0:06:40.440 --> 0:06:44.400 Yeah, the winter is twenty four to seven darkness. But 0:06:44.760 --> 0:06:47.000 it's kind of amazing because you get the northern lights 0:06:47.080 --> 0:06:48.800 the whole time, Like in the middle of the day, 0:06:48.880 --> 0:06:51.159 you'll be like walking to work to do this. 0:06:51.320 --> 0:06:54.760 Is amazing lights in the sky. Wow. 0:06:54.920 --> 0:06:58.320 So I think I in terms of like sleeping, the 0:06:58.400 --> 0:07:01.960 winter is so much easier just because it's dark all 0:07:02.000 --> 0:07:02.400 the time. 0:07:02.600 --> 0:07:05.000 It's kind of nice. But in the summer, we play 0:07:05.120 --> 0:07:07.280 Operation Nighttime in my house. 0:07:09.080 --> 0:07:11.679 Because you guys have to like just close all the windows, 0:07:11.680 --> 0:07:14.680 all the cuts, put like copboard onto block out the light. 0:07:14.720 --> 0:07:16.760 At like ten pm, just run around the house play 0:07:16.840 --> 0:07:19.240 Operation Nighttime so you can sell my God. 0:07:20.080 --> 0:07:23.600 So I'm guessing Operation Nighttime is a technique for adapting 0:07:23.640 --> 0:07:26.520 to the constant light. So can you walk us through 0:07:26.560 --> 0:07:27.800 exactly what that looks like. 0:07:28.560 --> 0:07:31.720 Yeah, So when it hits ten pm. I have a 0:07:31.720 --> 0:07:34.200 little alarm on my phone to remind me to do it. 0:07:34.680 --> 0:07:37.320 Otherwise I just yeah, I have no idea that it's 0:07:37.520 --> 0:07:38.080 that time. 0:07:38.480 --> 0:07:41.480 And then go around and we have like blackoutlines on all. 0:07:41.400 --> 0:07:45.760 Of the windows, So me and my housemates we go 0:07:45.800 --> 0:07:48.800 around and like cover room each We just go and 0:07:48.840 --> 0:07:51.240 pull them all down. And the most important one I 0:07:51.280 --> 0:07:54.040 always forget is to close my bedroom cuts. 0:07:54.120 --> 0:07:56.360 So when I go into my bedroom, it's dark. 0:07:58.240 --> 0:08:00.840 But yeah, it's just remembering to do it, sitting a 0:08:00.840 --> 0:08:05.679 long and pulling those blackout clients down, making a night time. 0:08:06.920 --> 0:08:09.480 It sounds like a great way to recreate night and 0:08:09.680 --> 0:08:13.000 also a pretty interesting reminder of just how important the 0:08:13.080 --> 0:08:16.400 darkness is to signaling sleep mechanisms in our brains. But 0:08:16.480 --> 0:08:18.840 prepping the house is one thing. What's it like to 0:08:18.880 --> 0:08:19.880 work in this environment? 0:08:20.680 --> 0:08:24.640 I mean, gardening is very seasonal anyway, but it's more 0:08:24.960 --> 0:08:30.320 extreme here. So the gardening season now starts in May 0:08:30.400 --> 0:08:31.480 when it gets warm. 0:08:31.320 --> 0:08:33.520 Enough because we just get the light back then. 0:08:34.200 --> 0:08:36.880 And then in September is when we start to get 0:08:36.960 --> 0:08:39.600 what you call the average day with like a normal 0:08:39.600 --> 0:08:42.240 sunset sunrise kind of thing. But that's when it starts 0:08:42.240 --> 0:08:45.079 to get really cold here through the summer. It's amazing. 0:08:45.280 --> 0:08:48.160 I'm working in the greenhouse. The plants love the twenty 0:08:48.200 --> 0:08:51.520 four hour daylight really crazy. 0:08:51.760 --> 0:08:55.320 So I'm curious how the plants respond over there to 0:08:56.040 --> 0:08:58.840 these periods of extended sunlight and darkness. 0:09:00.040 --> 0:09:01.000 Veggies especially. 0:09:01.240 --> 0:09:03.480 You'll look on the back of a seed packet radish 0:09:03.520 --> 0:09:07.000 does normally be like one to two months to get 0:09:07.200 --> 0:09:10.200 a fully grown radish for the good old salad. 0:09:10.800 --> 0:09:14.599 Here it's like three weeks. Wow, everything grows crazy. 0:09:14.240 --> 0:09:18.600 Fast, incredible. So the plants love the summer, But what 0:09:18.640 --> 0:09:21.000 does life look like for the people here with such 0:09:21.080 --> 0:09:22.480 dramatic shifts and seasons. 0:09:23.000 --> 0:09:27.360 Honestly, you really recognize the shift in people's like behavioral. 0:09:26.840 --> 0:09:28.440 Patterns, which I find really interesting. 0:09:28.960 --> 0:09:29.240 Really. 0:09:29.520 --> 0:09:33.640 Yeah, So in the summer, people are like active, going 0:09:33.679 --> 0:09:35.840 for a walk. You spend like so much time on 0:09:35.880 --> 0:09:38.000 the land and like you're out as much as you 0:09:38.080 --> 0:09:41.679 possibly candy, And we're in a delta here too, so 0:09:41.720 --> 0:09:45.200 there's so much water and lakes and rivers, so people 0:09:45.800 --> 0:09:49.720 are often at like in canoes on a boat, and 0:09:49.920 --> 0:09:51.880 you just spend as much time outside as you can 0:09:52.120 --> 0:09:56.160 all like, yeah, it's amazing. And then as you like 0:09:56.360 --> 0:10:00.720 shift into getting colder and then in the so everyone 0:10:00.760 --> 0:10:02.120 basically just hibernates and. 0:10:02.080 --> 0:10:05.000 Does crafts, does crafts. 0:10:05.080 --> 0:10:08.120 Yeah, keep yourself busy during the like the winter months. 0:10:08.240 --> 0:10:11.720 That's a traditional thing as well, Like crafts and making 0:10:11.760 --> 0:10:16.040 things is a very big winter tradition, especially for the 0:10:16.040 --> 0:10:20.400 women appear too, because there's just less hunting and less 0:10:20.600 --> 0:10:23.200 gathering you can do on the land. That's true of 0:10:23.280 --> 0:10:27.200 people's like natural rhythms too. When it gets really cold outside, 0:10:27.240 --> 0:10:29.120 you're like, okay, conserve the energy. 0:10:29.640 --> 0:10:32.800 So what about holidays or celebrations. Is there a way 0:10:32.800 --> 0:10:36.000 that everyone ushers in these huge seasonal changes. 0:10:36.880 --> 0:10:40.640 So as soon as the sun rises for the first 0:10:40.679 --> 0:10:44.880 time in a month January sixth this year, and we 0:10:44.920 --> 0:10:49.240 have a massive sunrise festival, so everyone comes out. Only 0:10:49.320 --> 0:10:53.040 rises for like maybe thirty seconds, so it's still really dark, 0:10:54.480 --> 0:10:57.680 but everyone comes out and celebrates and we have like 0:10:57.960 --> 0:11:03.440 fireworks and everyone makes food and we hang out and yeah, 0:11:03.440 --> 0:11:05.920 because the population is very small, so it's like three 0:11:05.960 --> 0:11:08.439 thousand people, and the same thing in the summer, we 0:11:08.559 --> 0:11:12.560 have like winter markets with the town. So there's always 0:11:12.600 --> 0:11:14.920 like a really big celebration in the winter and the 0:11:14.960 --> 0:11:18.560 summer just of like hey, this is the longest day 0:11:18.920 --> 0:11:22.320 of the whole year technically, and this is the first. 0:11:22.120 --> 0:11:23.120 Sunrise of the year. 0:11:23.240 --> 0:11:26.880 Let's celebrate these things because it's amazing that we get 0:11:27.280 --> 0:11:29.439 light back all like the light then goes away. 0:11:30.400 --> 0:11:33.960 And what about the people there who've lived there for 0:11:34.440 --> 0:11:38.080 decades or centuries. Have there been any ways that they've 0:11:38.080 --> 0:11:39.640 been affected by this kind of living? 0:11:40.480 --> 0:11:44.680 Yeah, I mean, I know, maybe not even just Canada, 0:11:44.760 --> 0:11:49.560 but across the entire like circumpolar and circum Arctic globe 0:11:49.720 --> 0:11:53.480 that does a thing called midnight summer craziness. 0:11:54.360 --> 0:11:55.760 So people people do. 0:11:55.800 --> 0:11:59.080 Go a little bit lupylo and in the summer just 0:11:59.080 --> 0:12:01.800 because you just don't sleep as much. But I know 0:12:01.920 --> 0:12:05.360 that in the past, and this is speaking just from 0:12:05.880 --> 0:12:12.240 general knowledge that people generally who were indigenous and lived 0:12:12.559 --> 0:12:18.520 on the land were really good at just following the 0:12:18.559 --> 0:12:21.680 animals and living with their families and kids are just 0:12:21.720 --> 0:12:25.520 playing out at like five am, like two am because 0:12:25.840 --> 0:12:28.520 it doesn't really matter. So people have more of like 0:12:28.559 --> 0:12:32.000 a nap culture and kind of just sleep whenever. 0:12:31.640 --> 0:12:32.040 They want to. 0:12:33.760 --> 0:12:37.079 So do you feel like you've adapted to this, like 0:12:37.120 --> 0:12:39.600 your circadian rhythm, for example, has adapted to this, or 0:12:39.640 --> 0:12:43.160 is it something that's still jarring for you after several years. 0:12:42.920 --> 0:12:46.000 Of living in this Actually I kind of like it. Yeah, 0:12:46.040 --> 0:12:47.520 I think you've got used to it for sure. 0:12:47.960 --> 0:12:49.880 And what about your sleep quality? Do you notice the 0:12:49.880 --> 0:12:53.720 difference in your sleep when it's extended periods of sunlight 0:12:53.880 --> 0:12:56.280 versus extended periods of darkness? 0:12:57.000 --> 0:12:57.520 Definitely. 0:12:57.520 --> 0:13:00.880 At the beginning, Yeah, Like in my first maybe six 0:13:00.920 --> 0:13:04.480 months here, it was pretty difficult. But then I learned 0:13:04.520 --> 0:13:10.800 about operation Nighttime in the house. I've like really taken 0:13:10.840 --> 0:13:12.800 that to heart and employed that thoroughly. 0:13:14.280 --> 0:13:17.160 When I talked about the challenges that Addie faces with 0:13:17.280 --> 0:13:21.560 doctor Stephen Lockley, he reiterated the extremely important role that 0:13:21.600 --> 0:13:24.680 our eyes play and what the perception of brightness or 0:13:24.760 --> 0:13:26.880 darkness does in our brains. 0:13:27.920 --> 0:13:30.760 So the first thing to think about is what's happening 0:13:31.120 --> 0:13:34.200 at the eye as opposed to what's happened in the environment. 0:13:34.960 --> 0:13:38.160 It's the eye that detects the light to tell the 0:13:38.200 --> 0:13:41.360 brain whether it's day or night, which then in turn 0:13:41.440 --> 0:13:44.720 resets our circadian clock or twenty four hour clock, which 0:13:44.760 --> 0:13:47.400 then in turn tells the brain when to sleep, when 0:13:47.480 --> 0:13:49.480 to be awake, when to eat, and so on and 0:13:49.480 --> 0:13:52.600 so forth. The environment doesn't always match what happens at 0:13:52.640 --> 0:13:56.439 the eye. If you're in constant light, when you close 0:13:56.480 --> 0:14:00.000 your eyes, you create a light dark cycle at the eye. 0:14:01.160 --> 0:14:04.680 So the brain doesn't see constant light because you close 0:14:04.720 --> 0:14:05.280 your eyes. 0:14:05.040 --> 0:14:05.720 To go to sleep. 0:14:06.280 --> 0:14:09.880 So in that situation, closing your eyes then helps to 0:14:09.960 --> 0:14:11.439 reset our Cicadian clock. 0:14:14.760 --> 0:14:16.720 We'll be right back after a brief message from our 0:14:16.720 --> 0:14:27.320 partners at Mattress Firm, and now back to chasing sleep. 0:14:31.840 --> 0:14:35.640 Light or lack thereof, obviously plays an important role in 0:14:35.760 --> 0:14:38.520 not just the quality of our sleep, but the timing 0:14:38.520 --> 0:14:41.520 of it as well. We see effects on sleep from 0:14:41.680 --> 0:14:44.640 the sun and the lights in our homes, even the 0:14:44.720 --> 0:14:47.680 light from our cell phones. Addie has to black out 0:14:47.960 --> 0:14:51.800 her entire home every night when it's constant daylight. So 0:14:52.160 --> 0:14:55.040 what about the opposite of that, What sort of challenges 0:14:55.040 --> 0:14:58.960 would we see in our sleep living in constant darkness. 0:15:00.000 --> 0:15:02.240 Modern day? Obviously we have electric light, we have man 0:15:02.280 --> 0:15:05.040 made light. In the past, there may have been firelight 0:15:05.400 --> 0:15:09.160 or gas light, and so it would be unusual to 0:15:09.200 --> 0:15:13.200 be in complete darkness for that entire time. And again, 0:15:13.240 --> 0:15:16.160 if you create a light dark cycle through whatever source 0:15:16.160 --> 0:15:19.640 of light, you're providing a time queue to the brain 0:15:19.720 --> 0:15:22.640 to tell the brain when it's day or night. Now, 0:15:22.960 --> 0:15:26.360 there are scenarios that are similar to what you've just described, 0:15:27.120 --> 0:15:28.760 and for a lot of my career I've studied the 0:15:28.800 --> 0:15:32.120 impact of blindness on Cicadian rhythms and sleep. 0:15:32.240 --> 0:15:32.680 Interesting. 0:15:32.840 --> 0:15:35.280 So if you don't have eyes, or if you have 0:15:35.480 --> 0:15:39.240 an eye disorder which completely stops any light perception, then 0:15:39.280 --> 0:15:44.239 your brain is essentially in constant darkness. And in that situation, 0:15:44.680 --> 0:15:48.640 individuals have a disorder because they can't in train, they 0:15:48.640 --> 0:15:52.240 can't synchronize their daily clocks to a light dark cycle, 0:15:52.520 --> 0:15:54.800 and they in fact run on their own internal time, 0:15:55.160 --> 0:15:57.040 and that causes problems when you're trying to live in 0:15:57.080 --> 0:15:59.960 a twenty four hour world. So there are scenarios where 0:16:00.080 --> 0:16:04.000 people do live in complete darkness, but we always have 0:16:04.040 --> 0:16:06.960 to keep in mind what the environment is and then 0:16:07.000 --> 0:16:10.320 what the retina and what the eye is receiving. And 0:16:10.360 --> 0:16:12.920 so most of us still live in a light dark cycle, 0:16:13.480 --> 0:16:16.560 even if we're at those extreme northern latitudes. 0:16:17.600 --> 0:16:21.400 Got it, And I'm curious what role does melotonin play 0:16:21.440 --> 0:16:23.800 in all of this. It seems like melatonin, from what 0:16:23.840 --> 0:16:26.640 I understand, your body produces it based at least in 0:16:26.680 --> 0:16:29.560 part in light signals to the brain. 0:16:30.200 --> 0:16:34.400 With internal melatonin. Your natural melatonin doesn't need light or 0:16:34.520 --> 0:16:39.360 dark to be released. It's released automatically by the circadian clock, 0:16:40.040 --> 0:16:42.520 and so the clock sends a signal to the pineal gland, 0:16:42.520 --> 0:16:45.320 which is where melatonin is released from, and that will 0:16:45.360 --> 0:16:49.480 happen on a twenty four hour pattern even though there's 0:16:49.480 --> 0:16:52.000 no light dark cycle. So in the blind people I 0:16:52.040 --> 0:16:55.400 was talking about earlier, they still have a daily signal 0:16:55.480 --> 0:16:58.320 or a daily pattern of melotonin. It just can't be 0:16:58.360 --> 0:17:01.680 synchronized to the light dark cycle. But if you have eyes, 0:17:01.760 --> 0:17:05.600 if you can detect light, then melatonin cycles so that 0:17:05.640 --> 0:17:09.119 it's maximum at night and minimum in the daytime. It 0:17:09.160 --> 0:17:12.199 isn't a sleep hormone, which sometimes people often think it is. 0:17:12.880 --> 0:17:16.040 It's a darkness hormone, and so it tells the brain 0:17:16.520 --> 0:17:19.960 it's night now. In humans, that means go to sleep, 0:17:20.480 --> 0:17:23.520 and so melatonin means go to sleep. In humans, dark 0:17:23.600 --> 0:17:26.919 and sleep go together. And so what that melatonin signal 0:17:26.960 --> 0:17:29.720 does it helps the brain tell the difference between night 0:17:29.840 --> 0:17:32.959 and day. Now, if you shine a light at your 0:17:32.960 --> 0:17:36.879 eyes at night, then your melatonin will be stopped. So 0:17:36.920 --> 0:17:41.080 when the brain sees light, it thinks daytime. It suppresses 0:17:41.119 --> 0:17:44.200 your melatonin. It makes you more alert, it increases your 0:17:44.200 --> 0:17:47.400 heart rate, it increases your temperature because naturally the only 0:17:47.560 --> 0:17:50.359 time you would see light is in the daytime. So 0:17:50.440 --> 0:17:53.840 when we expose ourselves to light at night, we're confusing 0:17:53.880 --> 0:17:57.560 the body clock, we're confusing the brain because light means day. 0:17:58.760 --> 0:18:00.800 Another thing I wanted to ask you, which I find 0:18:00.840 --> 0:18:04.000 really fascinating, is there's been some literature more and more 0:18:04.000 --> 0:18:09.200 in recent years, looking into this phenomenon of bi phasic sleeping, 0:18:09.640 --> 0:18:12.879 where you know, before the dawn of electricity, people went 0:18:12.880 --> 0:18:15.120 to bed very early, as soon as the sun set. 0:18:15.640 --> 0:18:17.919 In many cases, you know, they may have woken up 0:18:17.960 --> 0:18:19.920 in the middle of the night to do all sorts 0:18:19.960 --> 0:18:23.840 of things by candlelight, or to do some agricultural work, 0:18:24.200 --> 0:18:26.480 and then would go back to sleep until the sun 0:18:26.520 --> 0:18:29.160 came up. Do you have any thoughts on this phenomenon. 0:18:29.880 --> 0:18:33.600 It's very interesting observation and whether we've you know, what 0:18:33.640 --> 0:18:37.160 we've done to change our behavior in modern times. And 0:18:37.600 --> 0:18:39.720 first of all, we have to think again about light sources. 0:18:40.280 --> 0:18:41.960 You just said people got up to do things by 0:18:42.040 --> 0:18:44.879 candle light, Well, that wouldn't have a very big impact 0:18:44.960 --> 0:18:46.399 on your Cicadan rhythms. 0:18:46.480 --> 0:18:46.879 Or sleep. 0:18:47.520 --> 0:18:49.920 Ah, that's a good point. So even in a bi 0:18:50.000 --> 0:18:52.840 phasic sleeping cycle, you would still need a source of 0:18:52.960 --> 0:18:56.639 light for any period or being awake. It's not like 0:18:56.680 --> 0:18:58.639 this would be effective to get up in the middle 0:18:58.680 --> 0:19:01.040 of the night, say, and try to be productive in 0:19:01.080 --> 0:19:02.000 complete darkness. 0:19:02.840 --> 0:19:05.640 So these are low levels of light which have minimal 0:19:05.840 --> 0:19:10.160 impact on your circadian rhythms and alertness. If you expose 0:19:10.200 --> 0:19:15.439 people to a longer night, their melatonin profile lengthens, And 0:19:15.520 --> 0:19:18.399 so what the melatonin signal does in the brain is 0:19:18.480 --> 0:19:21.400 tell the brain how long night is. In the summer, 0:19:21.480 --> 0:19:24.919 you will have a shorter scoto period, a shorter night period, 0:19:25.440 --> 0:19:29.200 and produce melatonin for a shorter time. Then in the winter, 0:19:29.520 --> 0:19:32.919 as you expand the night, your melatonin profile expands and 0:19:32.960 --> 0:19:37.560 gets longer. So humans still have the capability to change 0:19:37.640 --> 0:19:42.000 their biology based on season through this change in melatonin. 0:19:42.440 --> 0:19:44.600 And what probably happened is if you don't have electric 0:19:44.680 --> 0:19:47.000 light to stay up, you would go to bed earlier. 0:19:47.160 --> 0:19:49.640 You could all try that yourselves, don't turn an electric 0:19:49.720 --> 0:19:52.080 light on after dusk and see if you go to 0:19:52.080 --> 0:19:55.120 bed earlier. I suspects you probably will if you've gotten 0:19:55.200 --> 0:19:57.560 nothing to do but lie in bed in the dark, 0:19:57.760 --> 0:20:00.960 the chances are you're going to sleep for longer. And 0:20:01.040 --> 0:20:05.040 we override each and every day on natural biology by 0:20:05.080 --> 0:20:09.160 having access to light after dusk and no light after 0:20:09.240 --> 0:20:12.920 dusk is normal. We would never see substantial amounts of 0:20:13.000 --> 0:20:16.639 light after dusk with a natural light dark cycle. So 0:20:16.760 --> 0:20:19.200 all of it is changing our biology. And in fact 0:20:19.200 --> 0:20:21.439 what's happened is all of us are shifted later than 0:20:21.440 --> 0:20:23.640 we should be. We all go to bed too late 0:20:23.720 --> 0:20:26.440 based on the natural rhythms, and we all probably sleep 0:20:26.520 --> 0:20:28.840 less than we would have done in the past, at 0:20:28.920 --> 0:20:30.359 least based on that natural cycle. 0:20:30.960 --> 0:20:34.640 So bi phasic sleeping was likely the natural result of 0:20:34.680 --> 0:20:37.159 the day night cycle in a world with little or 0:20:37.200 --> 0:20:40.639 no human made light sources. And as we evolved and 0:20:40.720 --> 0:20:44.520 built electric light, and we began using light sources like 0:20:44.560 --> 0:20:48.919 our smartphones, we fundamentally changed our day night cycle. I 0:20:48.920 --> 0:20:53.720 guess that really shows just how incredibly impactful perceptions of 0:20:53.800 --> 0:20:58.280 light and dark are on our brains. But I am curious, 0:20:58.640 --> 0:21:01.600 are there other aspects of our biology that can be 0:21:02.160 --> 0:21:06.080 disrupted by these types of extreme day night cycles. 0:21:06.800 --> 0:21:09.920 Yes, so the Cicadian clock, the twenty four hour body clock, 0:21:09.960 --> 0:21:13.080 controls much more than sleep and so we know that 0:21:13.119 --> 0:21:17.320 the clock will control many hormones. We've mentioned melatonin, Cortisol 0:21:17.480 --> 0:21:22.360 is another strongly circadian hormone. But the patterns of your performance, 0:21:22.440 --> 0:21:28.080 your mood, your immune function, reproductive function, metabolism, both glucose 0:21:28.119 --> 0:21:33.000 and lipid metabolism, bone metabolism, many of these body systems 0:21:33.080 --> 0:21:36.479 are controlled by your cicadian clock in the brain and 0:21:36.520 --> 0:21:40.160 also cicadian clocks that we have in the periphery. And 0:21:40.240 --> 0:21:43.520 so if you have disruption of the clock, mainly through 0:21:43.600 --> 0:21:46.320 a change in light dark cycles, then all the other 0:21:46.359 --> 0:21:48.720 body systems that are controlled by the clock will also 0:21:48.760 --> 0:21:52.000 be disrupted. And so if we use shift workers as 0:21:52.000 --> 0:21:56.119 an example of cicadian disruption, we find that shift workers 0:21:56.119 --> 0:21:59.200