WHOOP Podcast - What Time is It? How to Navigate Shift Work, Jet Lag, and Changes to Your Circadian Rhythms with Dr. Greg Potter

Episode Date: November 30, 2022

This week, we are diving deep into the science behind circadian rhythms and shift work. WHOOP VP of Performance Science Kristen Holmes is joined by sleep expert Dr. Greg Potter. Dr. Potter is here to shed light on the secrets of regulating circadian rhythms and his research around sleep, nutrition, and metabolism. Kristen and Dr. Potter discuss the risks of shift work on the body (3:50), the optimal timing for employers to schedule shift work employees (8:55), the process of sleep homeostasis (13:55), the circadian process (14:53), what zeitgebers are and how they influence circadian rhythms (17:51), how to shift your biological clock (23:56), how to schedule your meals (27:29), the positive and negative effects of caffeine consumption (31:18), developing a pre-bed relaxation routine (36:46), melatonin and other supplements for sleep (38:42), the best ways to restrict light exposure (42:36), the L-Glycine and L-Theanine proteins (45:36), how exercise can aid metabolic health (47:09), and how to manipulate zeitgebers to adapt to a new time zone and dealing with jet lag (51:38).Resources:Dr. Greg PotterCheri Mah's Study on Sleep and Athlete PerformanceClaudio Moreno's Study on Melatonin Support the showFollow WHOOP: www.whoop.com Trial WHOOP for Free Instagram TikTok YouTube X Facebook LinkedIn Follow Will Ahmed: Instagram X LinkedIn Follow Kristen Holmes: Instagram LinkedIn Follow Emily Capodilupo: LinkedIn

What's up, folks? Welcome back to the WOOP podcast, where we sit down with top athletes, researchers, scientists, and more to learn what the best in the world are doing to perform at their peak. And what you can do to unlock your own best performance. I'm your host, Will Ahmed, founder and CEO of Woop. We are on a mission to unlock human performance. All right, on this week's episode, our VP of Performance, Kristen Holmes, is joined by, Dr. Greg Potter. Dr. Potter is an expert in circadian rhythms and sleep with an undergraduate and master's degree in exercise science from Loboro University. His PhD research at the

University of Leeds focused on sleep, circadian rhythms, nutrition, and metabolism. Dr. Potter's research on circadian rhythms and sleep has been published and featured in media outlets, including Time, BBC, Reuters, and the Washington Post. Dr. Potter and Kristen discuss what circadian rhythms are and how they affect the body. What a zeitgeber is and how it relates to one's circadian rhythms. Some of the ways shift workers can deal with the changing of light exposure to regulate circadian rhythms. Ways shift workers can optimize their nutritional habits. The potential long-term health effects of sustained shift work. Tips on how to exercise and sleep right working difficult schedules and the effects of travel and time zones on a person's sleep and recovery. This is a great

overall sleep podcast. A reminder, if you're new to Whoop, you can use the code Will, W-I-L, when you're checking out to get a $60 credit on WOOP accessories. That is join.Woop.com to get started. We also just launched our most premium supernip band, so you can head to the shop and add some sparkle to your wrist. It's got 12 crystals embedded in the metal clasp, available in gold or rose gold. If you have a question you want to see answered on the podcast, email us, podcast at Woop.com, or call us 508-443-49-5-2, and it might just be answered on a future episode. Here are Kristen Holmes and Dr. Greg Potter. I think at this point, it's very well-documented in literature that shift work can cause

serious negative long-term effects. But the goal of today's podcast is not to terrify folks, but to rather focus on the modifications that individuals can make with regard to the timing of light, meals, supplementation, and exercise that can greatly reduce the burden shift work poses to the system. Here with me today, to summarize a lot of the research and put it into very practical terms is Dr. Greg Potter. Greg is a specialist in sleep, circadian rhythms, nutrition, and metabolism. He is a personal trainer, sports massage therapist, and has worked as a coach for over a decade.

What got me really excited about Greg is I was inside this literature and I saw a piece that he'd published that was entitled The Future of ShiftWorks, Circadian Biology, Meets, personalized medicine, and behavioral science. And I had our folks at Whoop reach out to Dr. Potter because we'd been wanting to do this episode for such a long time. I think, you know, our members have really expressed a lot of interest in, you know, how do we deal with shift work? You know, we talk a lot about sleep on the platform and how important it is and these folks are just not getting enough of it and quality and, you know, really are interested in strategies and tips that we can, we can deploy to kind of help

mitigate some of the effects. So Greg, we're so thrilled to have you on the podcast today to talk through some of these really tactical things individuals can do to offset some of these impacts. Great to be here, Kristen. So, you know, as I said, I don't want to terrify folks, but I think it's, it is important to set the stage in terms of understanding, you know, just the consequences of shift work. And really the goal with kind of raising some awareness around this is, is more to hopefully inspire folks to make some of these subtle modifications. So why don't you just give us a kind of a lay of the land in terms of what's happening when our circadian rhythms are desynchronized? I'll try and be relatively concise,

but how shift work affects your health and your well-being depends on lots of different factors. So there's your biology, how old you are, your general health and so on. There are the work demands, which also include things like whether you commute to the shift or not, your work schedule. There are the rewards that you get for the work. So whether you're compensated appropriately, your social support and much more. And because of variation, those factors, some people thrive when they do shift work. and other people have quite hard time. But in terms of what we know about health consequences,

we can break this down into a few different sections. So one is accidents. And in part because shift workers are often more sleepy than their non-shift working counterparts, they are at higher risk of certain types of accidents. They probably have something like 50 to 100% higher risk of many of those. And those risks are exacerbated by a few things. one of them is having very long shifts such that people who work shifts that are longer

than about 10 hours or so are much more likely to have accidents than people working shorter shifts. But then there are the effects of shift work on health and risk of various different diseases. And compared with non-shift workers, people who work shifts are at high risk of developing health issues such as the metabolic syndrome, type 2 diabetes, stroke, coronary heart disease, they seem to be a higher risk of asthma. And they also have some behavioral issues too, and perhaps because of that, they're more likely to abuse substances such as alcohol. How risky shift work is depends on a few factors such as chronotype, which we might come around to later. But just as an example of this, there was a very large-scale study of female shift

workers. And what it found was that while morning types, so larks, if you like, were a lower risk of developing type 2 diabetes when they were working day shifts than people who are intermediate chronotypes, people who are night owls who are working those day shifts were at much higher risk. So related to that, if you can remove the shift that's most strenuous for a given chronotype, which would be a night shift for an early bird or a morning shift for a night owl, then that's likely to have some bearing on the degree to which shifts are problematic. And then there are also some systemic factors that are going to influence whether shift work is bad for individuals and things that organisations can act on.

So as an example of this, just notifying workers in advance of their shifts might have some positive effects on their health. and some US cities have recently passed some laws to uphold fair working conditions. And there's a very interesting paper that was published looking at Seattle. And in 2017, Seattle became the second of these cities. And what they found was that when the organizations in Seattle started letting their workers know their shifts a couple of weeks in advance, the workers had improved sleep, higher subjective well-being. that economic security was higher too. So I don't want to sound like I'm fear-mongering or

anything like that, but I end on that note because there are things that people can do to help mitigate those risks of shift work. Yeah, I think that's such an important point. You know, it's control is one of the most important psychologically needs we have as human beings. And when individuals don't feel as though they have control over their schedules and over their life, things start to unravel really quickly. And I think what I love about, podcasts and these type of forums is that I feel like this type of information around kind of physiology and psychology and really bubbling to the surface. You know, what are the core kind of physiological needs that we have? What are the core psychological needs and kind of helping people

who are creating policy to better understand that there are just really subtle, easy things that we can do that have an outsized impact on people's health and well-being. And I love that you kind of landed on control because I just feel like when we don't have control, that really moves around our psychology in such a profound way. And that seems like kind of a simple thing for the most part that, you know, kind of employers can do for their workers that really will have, you know, just, I mean, you think about the planning, you know, that it goes into having to prep for being awake during the night and asleep during the day when you have a family. So maybe talk a little bit about that piece, just kind of the planning piece. Would you say that two weeks is about

what you would need in order to kind of shift your rhythms? What kind of would be the optimal I suppose work schedule. If, you know, if night shift is inevitable, is it a two-week block, is it a four-week block? Maybe just kind of walk through some of the research and just the science behind what would be optimal there. Sure. A few things are worth mentioning. So one is that sometimes you make changes based on first principles and things don't work out the way that you expect them to. And there are some instances of that in the literature. But with that said, we do know a few things. One of the questions that you asked was how quickly can you shift various circadian rhythms. We might come back to this later, but I actually think the instance of jet lag is a nice

example of this. And if you look at what happens during jet lag, then it seems that on average when people fly to the west, they can adjust their body's clocks at a rate of roughly two time zones per day. So if I was flying to the West Coast, of the US and the time difference was eight hours, then that might take me four days. However, if I was flying east, it seems that people can probably only shift their clocks at a rate of roughly one hour or so a day. And one of the reasons for that is that if you take people and you put them in so-called temporal isolation in which they have no idea what time day it is, they're exposed to a constant dim light, they're fed, isocholaric snacks, on the hour,

every hour, there's no variation, temperature, or anything. And so they don't have any time queues. What you find is that their circadian rhythms are actually slightly longer than 24 hours on average. And so it's easier to stay up later than it is to go to bed earlier. Now, another part of your question was, what are some different criteria that organization should stick to when it comes to choosing appropriate shift schedules. I think one of the helpful starting points for this is something that was implemented in Europe a few years ago, and it's called the European Working Time Directive. And they set out various different stipulations for businesses that are based here in Europe. So, for example, workers are supposed to have a break for at least 20 minutes

during shifts that are longer than six hours, they should have at least 11 hours of rest per 24-hour cycle. They shouldn't do more than 48 hours of work in total per week. And if they're working nights, then they shouldn't do more than eight hours of heavy or dangerous work per 24-hour cycle. But I think that there are a few different things that we can probably add in the mix, too. So, for example, earlier I mentioned that if you look at accidents, longer shifts associate with higher risk of various accidents, such as road accidents. And so I think limiting individual shifts to know longer than about 12 hours, is a smart starting point for most people.

Workers obviously need more recovery after strenuous, long shifts than they do after shorter shifts. And you also need to consider how many shifts people are doing consecutively, because because it does seem that accident risk increases with consecutive shifts. And so if somebody has done, say, five shifts on the trot, then they might need a longer period of rest thereafter than if they'd only done three shifts consecutively. And then I think also considering when people are finishing their shifts

and when other people are starting their shifts can be helpful. Because if you can schedule some overlap between people, then you can help minimize the risk of things going wrong. And then finally, adding some flexibility and giving people some autonomy over their shift schedules. So letting them slightly tweak their shifts depending on things such as childcare. And also, as I mentioned, ruling out the most strenuous shift for a given chronotype, all of those things I think can further improve the ability to match. shift schedules to a person's chronotype. The final thing that I'll mention, just circling back to

what I alluded to when I was discussing how quickly you can shift your rhythms is that forward rotating shift schedules in which you go from, say, a morning shift to a day shift to a night shift tend to work better than backward rotating ones. And again, that relates to the fact that it tends to be easier to stay up later than it does to go to bed earlier. Yeah. And maybe just talk quickly what's happening, you know, physiologically there, you know, when we think about adrenaline and cortisol. And I think your point or your kind of initial example, I think for most of us who are traveling west, to your point, it's easier to stay up and kind of push past, you know, that sleep pressure as opposed to traveling the other direction where you have to fall asleep earlier.

Maybe just explain what's going on there. And then let's get into kind of strategies and how to think about how we can kind of manipulate the system to kind of be better positioned to deal with jet lag even, but really specifically shift work. One thing that might be worth mentioning here is how sleep is regulated, and we can model sleep by way of the interaction of two processes. One of these is called sleep homeostasis. All this is getting at is that our bodies like getting a certain amount of sleep. And so they try and protect how much sleep they get per 24-hour day.

So if, for example, you deprive somebody of sleep entirely one night, the following evening, you'd expect them to partially compensate for that by sleeping more in total. And so related to this, in general, the longer that you've been awake, the sleepier that you feel. This, again, is one of the reasons why it's easier to stay up later and then sleep well than it is to go to bed earlier because when you stay up later, you've accumulated more of that pressure to sleep, which is going to help you fall asleep quickly and then stay asleep. The other process that influences our sleep is this circadian process. Circadian just means about a day.

It means roughly 24 hours. And this circadian process influences wakefulness. And so if you think about the fact that from the moment you wake up in the morning to the moment you fall asleep at night, you've got this pressure to sleep that's accumulating, you would expect yourself to feel more and more sleepy over the course of the day. But that isn't the case. What actually happens is that the circadian process produces an increasingly strong drive to be awake during the day to counteract that increase in sleepiness that's taking place. And interestingly, that dip in alertness that you feel around lunchtime, the so-called post-lunch slump, isn't so much related to what you've eaten at lunch.

It's actually more related to the fact that there's a temporary dip in the drive to be awake around this time of day. And that probably has an evolutionary basis because if you think about our ancestors, is living out on a savannah in a hot climate, it makes sense to get out of the sun's rays when the sun is highest in the sky at the hottest time of day because those rays are damaging. And so that's why if you look at siesta cultures, many of them will have a nap in the early afternoon in the summer during the hot months and then during the winter, that naps no longer present. But I digress. And so if we can understand those two processes, then we can understand something about the different sleep schedules that are easiest for our body.

and also it's important to recognize that different behaviours will influence how sleepy we feel. So take the example of flying west or trying to shift from a day shift to a night shift. There are things that we can do to boost our alertness that are going to make that process easier. So for example, if you consume high dose of caffeine late in your biological days, so say that you normally go to bed and fall asleep at 11pm and you have a double espresso at 9 p.m. 2 hours before bedtime. That's both going to reduce that pressure to sleep that's accumulated with prior weightfulness, but it's also going to independently shift your body's clock slightly later. There aren't so many agents, though, that will have the opposite effect

that are going to pull the body's clock earlier. And so the fact that we can use things like caffeine and increases in physical activity also contribute to why it's easier to adapt to that type of forward rotating schedule. So I'll pause there, Kristen, just in case there's anything you want to pick up on. Yeah, that's perfect. I mean, this is a great segue to talk really in depth about these Zikekeepers and you've kind of identified, you know, identified one exercise and obviously caffeine has a huge influence and can move around our circadian rhythms. But maybe just talk broadly about, okay, what are these Zikebors and, you know, how does it relate to our circadian rhythm? And then think about these in the context of shift work and how we can move them around to help us

adapt to, you know, coming onto a shift or going off a shift. Absolutely. Cicadian rhythms have a few characteristics. So, for example, they are untrainable, which means that you can speed them up or slow them down. And when you think back to the fact that typically the human biological clock doesn't tick at precisely 24 hours each day, it's closer to about 24 hours and 12 minutes on average. This matters. We need to be able to synchronize them each day.

And the way that we do this is through zeitgebers. And that's just a German word that literally means time giver. But they are time queues that help align our biological rhythms each day with the world around us. And humans, we are endothirms, our body temperature is roughly constant. And so because of that temperature isn't a strong time queue for us. And the strongest time queue for the human circadian system is the light dark cycle. And so what that means is that if we expose ourselves to lots of high intensity, short wavelength, rich light, which is the kind of light that you get outdoors on a sunny day, then depending on when we get that light,

we can move our clocks earlier or later respectively. It might be worth just briefly explaining how this relates to the circadian system and how this is regulated. So within your circadian system, you have a network of different types of clocks. And within this network, there is a so-called master clock in the brain, the super-chismatic nucleus. And a helpful analogy is to think of this master clock as being a bit like the conductor in the orchestra, because you have clocks probably in every cell in your body. And one of the issues is that if these clocks or the different instruments in the orchestra,

aren't playing in time with each other, then you're just going to have this dysphonic mess rather than having some sort of beautiful melody. And so what this master clock does is it uses different mechanisms to keep these other clocks in time with each other. And this master clock in the brain is most responsive to light exposure. And when considering light exposure, the intensity of the light matters so in this room right now the intensity of light is probably something like 500 lux whereas outdoors on a clear sunny day it might be 200 times that there is the spectrum of light so I mentioned earlier that short wavelength rich light is most effective at shifting our body's clocks and typically that appears blue to us but if it's full spectrum light

it might look white or something like that and then there's the timing too and whether your body's clock moves earlier or later depends on when you're exposed to light, in particular relative to the lowest point in your core body temperature. And so if you're exposed to light within about six hours before that low point, and this low point is roughly three hours or so before you'll naturally wake up in the morning. So let's say you naturally wake up at 7 a.m. Your core body temperature minimum is going to be at about 4 a.m. And if you expose yourself to lots of this type of light in the six hours or so before that you're going to shift your clock later whereas if you expose yourself to lots of this type of light in the six hours or so

after that core body temperature minimum so between 4 a.m. and 10 a.m., you're going to shift your clock earlier. But there are some other tightgebbers too for your clock. So whereas the light dark cycle is the main time queue for the master clock in the brain, it seems that exercise does influence the timing of this clock too. There's not so much research on this, but there's been some very nice work done by people such as Sean Youngstead in recent times, showing that how exercise shifts your clock is roughly the same as how light shifts it too. So if you exercise shortly after waking up, then you can shift it earlier, whereas if you exercise late in the day, you can shift it a bit later. And then exercise might also influence some of these clocks outside of the mast

clock in the brain, so-called peripheral clocks. In particular, the clocks in your skeletal muscle because the clocks in your skeletal muscle are going to influence things such as when your body is primed for exercise. And then finally, the other time cure, or zeitgeber that's very important in humans is the eating fasting cycle. Again, this hasn't been so well studied. And there are certain criteria that things need to meet to qualify as tightgebers. But certainly there's preliminary evidence that eating fasting cycles influence the timing of many of these peripheral clocks. And so what all of this means is that if we can get appropriate light exposure at the right times of day, coincide that with physical activity and align

that with our patterns of eating and fasting, then we can maintain a robust circadian system in which all of these different players in the orchestra are playing in time. And we are therefore behaving in a way that aligns those behaviors with when our bodies are optimized for them and thereby improve our health. So folks who are kind of not having to deal with the shift work, we are able to align all of these likekeepers with just the natural cues in the environment, i.e., when we're in the active phase of our circadian rhythm, which is basically when the sun is up, we're able to eat most of our calories. We want to get as much sunlight in artificial light, as much as light exposure as possible. And generally speaking, if we want to fall asleep earlier, we're going to

exercise earlier in the day. If we want to fall asleep a little bit later, we're going to exercise later in the day. So all of this is happening during the active phase. So what we're asking shift workers to do is basically take what they typically do in the active phase and do it during the inactive phase of their circadian rhythm, right? Is that kind of a correct characterization? Pretty much. Yeah. So for shift work, we basically want to take all the principles you kind of just talked about and basically apply that to, you know, what would be their typical biological night when they're going to be awake. Yeah, it obviously depends on the specifics of the shifts. Right. So if you had somebody who's switching from a day shift to a night shift and they were working

multiple night shifts on the truck in which they wanted to adjust their body's clocks to that new shift schedule, then it would make sense to try and delay their body's clocks by exercising relatively late in the biological day or the subjective day, eating in accordance with that to and exposing themselves to lots of light in that portion of the so-called phase response curve in which light is going to shift your clock later. So in the six hours or so before core body temperature minimum. However, if somebody was just working one night shift or two night shifts and was then reverting to day shifts, they might not want to fully shift their clocks. And instead, they might think, well, my performance during those night shifts is not the

most important thing to me. My health is. And so I'm going to do things that help me cope with these night shifts. However, in some ways, I'm going to maintain my behaviors in alignment with day shift because the majority of my time is spent on that schedule. And interestingly, even people who work permanent night shifts often struggle to fully align their body's clocks with night shifts. It's probably doable in a few very remote locations, so people working on oil rigs, that type of thing. But outside of those extreme circumstances,

most people aren't able to fully adjust their clocks to their night shifts. And so I think actually practically for a lot of people maintaining a relatively similar eating fasting cycle to people who don't work shifts is going to work relatively well for them. And there's been some wonderful work showing this recently published by Frank Shear and his colleagues, which basically took people through a protocol, which is designed so that after a few days, people are awake and eating during their biological night times. So metabolically, this would be the exact wrong thing to do. In another group of people, People are awake at that time, but they keep their eating fasting cycle in alignment with the

biological daytime. It's slightly difficult to explain. But what they find is that when they maintain their eating pattern back during the biological daytime, which for most people would be when the sun is up, when they're awake at night, they better maintain their blood sugar control. And they also have better mood, so lower measures of depression and anxiety than these people who are now eating during the biological night time. Yeah, completely.

I think I find that research really fascinating. And I think it has huge implications for folks who are managing surfwork and even for folks who are traveling. I know when I travel, I try to maintain my home time zone across the Zikegebers as much as possible. I mean, light is obviously really difficult. But, you know, using blue light blocking glasses and kind of being creative and strategic, you can kind of get partially the way there.

But I think the research that's emerging around meal timing, I think, is really. really interesting. And so really the strategy, if we were to kind of take that research and apply it to the real world, it would mean for individuals eating meals during the biological day as much as possible. So they're going to basically have, if they're working during the biological night, they're going to have a pretty narrow eating window, I would say, right? But that's when they want to consume a majority of their calories. Would that be the protocol? Yeah. So it might make sense just to think about an example. Take somebody who's normal sleep wake, schedule, but not working shift is to wake up at 7 a.m. and go to bed at 11 p.m.

They, in those circumstances, might eat between, say, 9 a.m. and 7 p.m. However, they periodically have to work nights. And so if they don't eat anything at all during that night shift, it might be difficult. So instead of that 9 a.m. to 7 p.m. eating schedule, they might just shift that slightly later, but not so late that it now overlaps with when they would normally be asleep when they're not working shifts. So, for example, they might eat between, say, midday and 10pm, because that is a schedule they can maintain both when they're working shifts and when they're not working shifts. And I think being pragmatic, if shift workers can try and restrict intake of any calorie containing items to a regular eight to 12 hour window each day, then they're likely to

experience some of the health benefits that have been shown to take place when people implement this type of time restricted eating in non-shift working context. And actually, Sachin Panda's lab has published some nice work on shift work as recently showing that this type of approach is feasible in shift work. And it does confer some health benefits too. So they looked at firefighters and they found that they lost a modest amount of weight, they had slight improvements in the average blood sugar levels, they had a reduction in diastolic blood pressure and some other beneficial effects too. And so I think if you can maintain that type of schedule and just think about trying to pin it to times of day that overlap with your work days and your non-work

days too. And then during those occasions when you do deviate and you do end up snacking during night shift C. I think it's just a question really of damage limitation. And if you can keep snacks at that time relatively small, so maybe no more than something like 10% of your daily energy intake, high in fiber, high in protein, probably low in carbohydrate, then you're going to minimally affect things like your blood sugar control. But by having small snacks at that time of day, you might experience some small benefits on things like your workplace performance. And so I think if you keep some healthy snacks handy for those occasions when you think you're going to have to eat something during your night shift, then that's probably going to benefit you.

And good examples of snacks might include things like natural yogurt, nuts, vegetables, maybe low sugar fruits as well. Bold eggs. Boiled eggs are great. Yeah. All right. That's really helpful. So restricting food access to the active phase.

So and just figuring out what that means because I think what happens is we get people who have lots of different types of shifts. So if we can just like bubble up the principle, it would be just thinking about your active phase, which is during the daylight hours, whatever that overlap is, getting a majority of your calories during that time frame. If you have to snack during the night on shift, prioritizing it to ensure that it's, you know, high protein, limit the processed foods and roughly 10% of your normal like caloric intake. Is that kind of the high level like summary? I think that's good bite's going.

Okay. Cool. Let's talk a little bit about supplements. I found your summary in the research paper really interesting. So let's talk maybe first. We talked a little bit about caffeine, but maybe just hit on the real specifics in terms of individual dosages and how to think about that in the context of when you want to go to sleep. And, you know, if you're transitioning from, you know, going from being on shift to off shift, what does that actually look like? Caffeine's a double-edged sword. Yeah. And if you use it judiciously, then it can be better. beneficial and even life-saving in some contexts.

And if you look at all the studies that have been done of sleep deprivation, sleep restriction, simulated shift work, then caffeine consistently improves things such as alertness, attention and reaction time. But of course, if you consume too much too close to sleep, then you're going to decimate your sleep and impair your ability to recover between shifts. With that in mind, I think in the context of shift, gift work frequent low doses of caffeine tend to work quite well. David Dinges has done some brilliant experiments looking at prolonged sleep deprivation showing that if you give people

regular very low dose of caffeine then they perform much better than when they don't get those and interestingly you also reduce the kind of groginess that you experience after napping when you have regular low dose of caffeine. So if you nap during your night shift, for instance, you might actually find that caffeine alleviates that groginess and means that you can return to performing fast than you otherwise would be able to. And so with respect to dosages and timing, I think that having something like 50 milligrams of caffeine every other hour, if you're struggling with sleepiness during a night shift, can be really helpful. 50 milligrams of caffeine is roughly the amount that you would get in an instant coffee. But there are also forms of caffeine in

which you know exactly how much caffeine you're getting. And for people who need very fast acting boost and alertness, caffeinated gum is particularly helpful. And the reason is that the gum delivery format speeds the entry of caffeine into the blood because you absorb more of the caffeine through the buckle mucosa in the mouth. And you also bypass some aspects of early caffeine metabolism too. And so having 50 milligrams of caffeine via gum, will give you a jolt and alertness within 15 minutes or so, whereas if you'd had that by a coffee, it probably would have taken something more like 45 minutes.

And then the other considerations are how much caffeine total per 24 hours? For non-shift workers, I typically recommend no more than about 3 milligrams of caffeine per kilogram of body weight per day. So if you are 70 kilos, which is 154 pounds, then that would be no more than 210 milligrams of caffeine per day. and that is roughly four instant coffees. There's a website Caffeine Informer.com

that's got the caffeine contents of many commonly consumed items. So if you want to estimate your caffeine intake, you can go there to find out more. But I think for shift workers, in particular people who need to maintain their safety during night shifts, it's worth allowing them a little bit more freedom with their caffeine intake. And I'd probably say that for most people

know more than about six milligrams of caffeine per 24 hours. in that context is a good way to go. And certainly you don't want any of that caffeine any later than about six hours before your main sleep out unless it's absolutely essential. And on that note, one strategy that can be really helpful is a so-called caffeine nap. And the idea here is that even a brief nap,

10 to 20 minutes of actual sleep, can quite potently boost your alertness and it can be very restorative. you can feel much less fatigued after such a short nap. But if you take a dose of caffeine, maybe something like two milligrams of caffeine per kilogram of body weight, immediately before the nap, then the caffeine won't have affected the nap

because it won't kick in fast enough to interfere with your ability to fall asleep. However, when you wake up from the nap, the caffeine will be starting to kick in. And so you end up with a two-pronger, way of boosting your alertness. So let's say that you have to drive home and you're feeling a bit sleepy late in the shift. You could have a 10 to 20 minute nap with a cup of coffee immediately before it. And then you could probably drive back half an hour later and be much

more alert and less likely to crash than had you not had that caffeinated nap. That's a great strategy and such a good call out. The napuccino we call it is really effective. And I think it can be Just offsetting, you know, sleep loss and insufficient sleep, I think, is, you know, it's like folks just need to try to fit in these, like, many moments of sleep and rest, you know, when sleep might not be as perfect as it can be. But I think the timing, you know, you mentioned, you know, six hours prior to when they intend to sleep, I think trying to hold themselves to that is probably important, right? Just because it can get into a vicious cycle of not being able to fall asleep and when they need to fall asleep and they kind of get in this loop. So, you know,

being strategic about the timing, I think is probably really important. In offsetting, potentially when we get in that kind of six-hour buffer using some non-sleep deep rest protocols, for example, like a yoga nidra, where they can kind of, again, have a technique that will make them feel rested and make up for some of that sleep loss, but without creating that groginess could also be a good strategy. Yeah, and I think it's important for shift workers to maintain a pre-bed relaxation. ritual because it's more difficult to do so in that context than it is for us non-shift workers. Most of us have an hour or two to unwind at the end of the day, ideally with loved ones.

But if you're finishing a night shift at seven in the morning, then you might not feel like having any time to unwind after that. But I think giving yourself ideally an hour or so and maybe using some of those types of techniques to help you quickly calm your nervous system can be helpful. And there are many of those listening to relaxing music is one that's been shown to be effective. Different forms of mindfulness meditation can help. And there are also some specific relaxation strategy such as progressive muscle relaxation that I won't go into now, different types of breathing exercises, some of which use biofeedback, which can also quite strongly shift your nervous system for

being in that fight, flight or freeze state to being in more of a rest and digest one. Right, right. Yeah, I think incorporating those breathing protocols, even prior to bed for sure to activate the paristhenic branch of the nervous system, but I think even during shift, you know, if there's just these many moments where you can do some extended short inhale and extended exhale, you know, to calm the nervous system, I think. Throughout the shift, I think can be another way to just mitigate some of that stress accumulation. That impacts our ability to fall asleep, you know, just kind of reminding ourselves to, yeah, to build those in into the day, I think it can be a really good strategy. It can also be really helpful for your performance

of work, too. Without a doubt, yeah. Let's talk a little bit about, so we're home from the shift. What's your recommendation around melatonin and, you know, some of the amino acids like glycine? How can those maybe help folks transition to sleep faster or, you know, what's your take on that? Melatonin is very interesting. It's a hormone that's, produced by the brain and it's weakly soporific it will slightly promote sleepiness but its effects on the circadian system is stronger and it's a so-called chronobiotic meaning that it can shift some parameters of the circadian system and if you take an appropriate dose of melatonin so say 300 micrograms to 5 milligrams of melatonin roughly 3 to 5 hours before you normally go to bed you'll

tend to pull your body's clock earlier, which will help you fall asleep earlier and then wake up early the next day too. Whereas if you take the same dose of melatonin around when you wake up in the morning, that's going to actually shift your body's clock later. And so you can use this to help speed the rate to which you adapt and changes in your shift schedule. However, obviously, you can also take it an inappropriate time and shift your clock in the wrong direction. And so with that in mind, it's quite difficult being very prescriptive when it comes to using melatonin. But it can help. And a really nice example of this was a study that's published by Claudia Moreno just last year.

And what her and her colleagues did was they had people take three milligrams of melatonin on non-shift nights. So these people were periodically working night shifts. And then when they weren't working night shifts, they took three milligrams of melatonin. an hour before bedtime. And what they found was that that was able to reduce circadian misalignment and led to some beneficial effects on their cardiometabolic health. But if we're focusing on the general population, melatonin isn't something that I would necessarily recommend because I just think that you have to factor in various different variables that are difficult to factor in when we're just talking about it in this type of context. So,

under the guidance of a healthcare practitioner, melatonin can be helpful. But if somebody's just tuning into this and they're a shift worker, I wouldn't necessarily recommend melatonin. If you're a non-shift worker, then melatonin is very safe. It has a fantastic safety profile as far as drugs go. The issue of melatonin, though, is that most melatonin people buy is over the counter in the US. And there is... Super physiological. It's like a dosages are just...

Yeah, it is super physiological typically. Although, interestingly, there doesn't seem to be the same negative feedback with melatonin synthesis that you see with some drugs. So, for example, if you're male and you take testosterone for performance and enhancing purposes, after a while you are going to shut down your body's own synthesis of testosterone. Melatonin doesn't really seem to be like that. The issue with over-the-counter melatonin is just that lots of the products don't contain what they say they do on the label. And there was a study a few years ago, which they took melatonin supplements off the shelves,

and they tested them for melatonin. They found that their contents varied from about 80% less than what was on the label to about 470% more than what was on the label. And some of the melatonin... Wow. Yeah, some of the supplements also contain serotonin. So you just have to find a good source

if you are going to use it. But that's an issue with the supplement industry in general and it is getting better over time. So melatonin, I wouldn't necessarily recommend it. Yeah. So we're talking about trying to fall sleep when you need you to fall asleep is kind of at the highest level. That's what we're trying to do, right? We're trying to be awake

when we need to be wake and sleepy when we need to be sleepy. You know, stress mitigation throughout the day. Some of the breathing protocols you mentioned would be helpful stopping caffeine consumption, six hours prior to when you intend to sleep. And then light restriction, you know, kind of in the lead up a couple hours prior to bed. What would be your recommendation in terms of things I can do to restrict light? And then just want to talk about alglycine too real quick. Yeah. So if you're outdoors, say that you're driving home and you're not overly sleepy, it's an hour and a half before you plan to go to bed. At that time, I would say, wear sunglasses or wear blue blocking glasses.

Wearing a cap will also... Pfizer. Yeah, wearing a cap will also slightly reduce your exposure to overhead light. And then when you're back at home, just modifying your light environment, in particular to reduce strong overhead white lighting is going to help. So if you have dimmers, you can use those. otherwise you want to ideally have lighting conditions which a lot of people describe as romantic lighting you want the kind of warm white light bulbs that you get in nice restaurants and there are actually

parameters that you can look for so if you're buying light bulbs for instance you'd probably want to buy light bulbs to have a colour temperature less than 3,000 Kelvin or so you also ideally would have those at eye level or below so just having lamps low in the environment is going to help reduce any overhead light that could shut down your body synthesis of melatonin and interfere with your ability to fall asleep through other mechanisms too and then in your bedroom get rid of any unnecessary source of light ideally won't have any device in your bedroom any way such as smartphones or laptops for shift workers i actually think they probably need to be slightly more attentive when it comes to light in the bedroom temperature of the bedroom and noise too because

Because if they're trying to sleep when the rest of the world is awake, then those are more likely to be disruptive. So blackout blinds can help. Having an eye mask can help. If you do have light emitting devices, then ideally get one to limit red light, which is much less likely to shift your body's clock and increase your alertness. And then when it comes to temperature, if you have aircon, then you can use that. Obviously, environmentally, that's quite problematic. You can just use a fan. having a cooling mattress and cooling pillows too, as well as a low tog rating duvet.

You can help you stay cool when outside it's quite hot. And then with respect to noise, you might want to try something like silicon earplugs to drown out any traffic that's going on outside or people shouting down the street and a thing that could wake you up. Right. That's terrific. Okay, Lglycine. This is a great, I think for folks who have been experimenting with Maltona, And again, I think that that talk to your healthcare practitioner, but generally speaking, we want to try to avoid melatonin, I think.

I don't think it's as benign as it's kind of made out to be. But this elglycine could be a good alternative, you know, in terms of shortening sleep latency potentially and just kind of helping with anxiety and whatnot. Yeah, going by the very limited research so far, taking something like three grams of lglycine, roughing an hour before bed, might have some small positive effects on some measures of sleep quality. It might also help you perform when you're not getting quite as much sleep as you need. But again, that is, with the caveat, that there really hasn't been that much research on that so far. In terms of other over-the-counter sleep agents, I think that one of the better ones is elthenin, which is the most abundant amino acid in tea. And al-thene, it acts through some pathways that are quite similar to how some commonly used sleep drugs act. but it has a fantastic safety profile.

Interestingly, it's also probably weekly neutropic. It can help in particular with attention during cognitive tasks. In terms of the dose, 200 to 400 milligrams a day, either as one or two doses with the final dose an hour before bedtime, might have some weak positive effects on sleep and possibly some other minor beneficial effects on other aspects of health too. And then people are always asking, me about things like magnesium too, and the evidence doesn't strongly show that magnesium is good

for sleep. However, most people just don't consume enough of it. And it's very clear that taking an appropriate dose of magnesium is very good for many aspects of cardiometabolic health. If you look, for instance, at all of the different metabolic syndrome criteria, magnesium has been shown to benefit pretty much all of them. So if you want to take magnesium as citrate or three and eight or bisglycinate shortly before bed than be my guest. That's super helpful. All right. Let's transition to exercise because we hit on light.

We hit on meal timing. We hit on some supplements, exercise. How should they think about that in the context of shift work? In many ways, my recommendations are quite similar to what they would be for non-shift workers, apart from the fact that exercise can be used to help you adjust to new shift schedules. And so if we think about exercise and its effects on health, then it's worth breaking it down into a few different components. So one is the type of exercise that you do, the modality. And we know that the combination of having high cardiorespiratory fitness and high skeletal muscle strength is associated with better long-term health outcomes than just having high cardiorespiratory fitness or strength, respectively.

And so I think it makes sense to develop both capacities. And if you look at pretty much any government exercise guidelines, then they all advocate for at least two resistance training sessions per week for major muscle groups. And so I think the total amount of exercise can be quite modest to get most health benefits from exercise if it's done intelligently. So with respect to strength training, that might just entail a few moving patterns, such as some sort of squatting pattern, some sort of hip-hinging pattern, an upper-body push and upper-body pull.

And you probably want to use certain training load. So, for example, you probably want to choose a weight that you can lift between maybe five and 20 times and exercise with the best form that you can exercise with, but go to within maybe one to four reps of failure or the point at which you lose your ability to maintain correct exercise, need in those. You also want to include some exercises that challenge your ability to maintain your

balance, particularly if you're past the age of 65 or so, because the excess mortality that's associated with things like hip fracture in elderly people is really striking. Six stability. Yeah. So just doing things like some single leg exercises can be really helpful. And then obviously exercising through a full range of motion is going to help you maintain your flexibility too. In terms of total time commitment, I think at least 75 minutes of vigorous intensity exercise or 150 minutes of moderate intensity exercise per week is fine, but certainly you can gain more benefits from doing more than that. Also, trying to insert some so-called exercise snacks or activity snacks into your day is going to be really helpful, in particular to

maintaining good blood sugar control. And so simple changes, like having a workstation at which you can stand can meaningfully improve some aspects of your metabolic health. If you can take a short walk after meals, then a walk of 15 to 20 minutes has been shown to improve how your body metabolizes those nutrients that you've just consumed. And these brief exercise snacks can also help you maintain your cognitive performance at work too. And then the other aspects touch on is just the timing. So like I mentioned earlier, if you're trying to move from working day shifts to work in night shifts, then scheduling some exercise probably not long before around the time at which you would habitually fall asleep. So going back to that 7am to 11 p.m., typical weightful routine,

if you exercised at around 9 or 10 p.m., then that would help you shift your clock later and adjust to that night shift schedule. Whereas if you are moving from, say, night shift to a day shift, exercising maybe in the late morning or around the day is going to help move your clock earlier. Perfect. We get a lot of questions from members around, you know, crossing time zones and we have a specific question from a long-haul pilot. What I'd love for people to come away with from this podcast is that all these principles that we're talking about can be applied to whatever your situation is.

So maybe if you just kind of summarize what we've talked about in terms of these zeitgebers and how we can manipulate them and kind of the framework that people should think about these zeitgebers, regardless of any time their circadian rhythms are going to be shifted, you know, how can they kind of think about these principles to really guide their decision making on, you know, how they can adapt to a new time zone or a new schedule or kind of maintain their current schedule. Okay, so the most important time cues are first and foremost, the light, dark cycle, exercise, and when you eat and when you fast. And if I was trying to create some sort of unifying framework for understanding how to time these different cues to shift your body's clock either earlier or later respectively, then it would probably make most sense to think about when you're engaging in those behaviors or those exposures. relative to your core body temperature minimum, which is typically about three hours before you'd naturally wake up in the morning. And so getting lots of high-intensity light exposure. So think daylight, but if you can't get outside, then getting something like a light therapy lamp,

the kind of lamp that you'd use for seasonal affective disorder, maybe one that emits 10,000 lux or so, could be used as a replacement for daylight and can be helpful in the context of shift work. but getting lots of that type of light between your core body temperature minimum six hours after that and then also doing some exercise at around that time of day is going to shift your clock earlier and then avoiding light and activity in the six hours before your core body temperature minimum the following evening is also going to help shift you earlier if however you're trying to shift

your clock later then you would want the light and the exercise in the six hours before you core body temperature minimum and you would want to avoid it in the six hours after that's slightly contrived i know but being very practical if you just think about a normal sleep wake cycle and waking up at 7 a.m getting outdoors and doing some activity in the three hours after you wake up in the morning is going to help shift you earlier and then being sure to avoid those things in a couple of hours before bed is going to help with that too whereas avoiding light in the morning. and avoiding activity in the morning and then getting some of both of those shortly before bed is going to help shift you later. And then with respect to your meal timing, you want to

try to maintain that during your subjective daytime, regardless of when that is. And the subjective daytime is basically when you feel your best. So it's the time of day at which you would naturally be up and about and awake and socialising and eating. And so trying to keep that eight to 12 hour eating windows within that time of day from day to day is going to help. And then one of the things that we haven't really spoken about is that sleep obviously gates your exposure to some of these other things too. And in shift work, shift work disorder is very common. And it's basically characterized by excessive sleepiness while awake and then difficult. sleeping at night. And it's because the two processes that we spoke about earlier, the circadian

process and the sleep process, the sleep homeostasis process, have lost appropriate relationships with each other. But if you have shift work disorder, then trying to keep consistent sleep timing from one day to next is also going to help with that. So thinking about times of day at which you can sleep during both shift days and rest days and trying to keep that. regular pattern and keep your regular food intake too is likely to help. And then finally, in the context of jet lag, it's a slightly different conversation because jet lag is really influenced by two things. One of them is travel fatigue, which is the kind of fatigue that you would get if you just drove within a time zone for several hours, but you were sedentary during

that time and you're exposed to lower oxygen levels in the air and maybe you had poor quality food and so on. And it's the fact that you're crossing multiple time zones quickly. So It's really the culmination of those two things. But to avoid going on, I'll just say that there are some freely available or relatively low cost tools out there that I think are really helpful. The one that I particularly like is called Jetlag Rooster by Sleepopolis. You can go to Sleepopolis and use Jetlag Rooster, which is a free web app. And basically you just enter where you're flying from, where you're flying to, whether you want to start adjusting your body's clock. in advance of going or when you begin your journey and whether you want to use melatonin

or not to help in that process and it will produce a personalized schedule for you which will recommend times a day at which to get light and times a day at which to avoid light and during those times when you want to get light be active at those times and when you need to avoid light use your sunglasses or blue blocking glasses if you're up and about and then final comment is in the context of jet lag with respect to your nutrition fully shift your time times to the new time zone when you land if you're trying to adjust to the new time zone. Yeah, I love that. The beautiful summary. Thank you so much. I travel a fair amount, so I'm kind of constantly experimenting. We've done some really cool case studies with some of our athletes who are

traveling from the East Coast to the West Coast, for example, and we basically just maintain their home time zone by keeping their meal schedule, exercise timing, and light viewing schedule on their home time zone. And we actually saw no physiological perturbations at all. And this particular team ended up winning national championship. It was a really happy story. Of course, they had a lot of talent, but I like to think that these protocols and the minimum disruption to their state ofadian rhythm had an impact. But I like the idea or the framework of, you know, when we're traveling, we kind of think about it in two buckets. We can either maintain our home time zone or we adapt to the new time zone. And that should set off this kind of cascade of

decision making around meal timing exercise, light viewing. And when we decide to go to Ben and we wake up, I think that's a kind of a perfect framework. Well, it's so nice to talk to you, Greg. Thank you for all your brilliant work. It is definitely very inspiring to me. Yeah, just hopefully we can find ways to work together. We have huge amounts of data. You know, we have a lot of subjective data that helps us contextualize our physiological data. So looking at, you know, meal timing, for example, could be of interest and getting some

questionnaires going that, you know, kind of pop up in the app. So, I don't know, think about maybe some research that you might be interested in doing and maybe we can set something up for the new year. Yeah, no problem. Thanks to Dr. Potter for joining us today and sharing his insights on sleep, circadian rhythms, and the impact of shift work. If you enjoyed this episode of the WOOP podcast, please subscribe, leave a rating or review. Check us out on social at WOOP at Will Ahmed.

If you have a question you want to see answered, email us, podcast at Woop.com. Call us 508-443-4952. New members can use the code Will to get a $60 credit on WOOP accessories. All right, that's a wrap. Stay healthy, stay in the green, and we will be back next week.