Daylight saving time will end Sunday, Nov. 1, and for many, that means an adjustment, unwelcome perhaps, in sleep. Other things can affect our sleep: children, pets, jet lag, work. And that brings us partly to our latest installment of our series, Balance, about health.
My co-host for this series, Jamie Baum, invited Tracy Anthony, professor of nutritional sciences at Rutgers University, to come to the studio to talk about circadian rhythms. Jamie Baum is an associate professor in the University of Arkansas Department of Food Science and director of the Center for Human Nutrition at the UofA. Tracy Anthony was here attending a conference on the UofA campus this week.
While our circadian rhythms are connected to different factors, Tracy Anthony says most of us connect circadian rhythms primarily to our sleep.
Anthony: Yeah, I mean, that’s pretty common. And it’s not wrong to think about your sleep quantity and quality and how that happens day in and day out. And rhythms are something that we just don’t spend time thinking about, because the world turns and we live on the earth. And so, sun up, sun down, we have this natural rhythm to our life.
And most people don’t realize that in our bodies, in our brains and in every cell of our body, we actually have a little timekeeper that keeps track of these rotations of our earth and help all of our body function. And circadian rhythm is essentially that concept that in your body, separate from any kind of stimulus that you encounter, you have this little timekeeper in your body cells, but in particular in your brain.
And in your brain, you just have this way to know this is day, this is night, and day in and day out, it keeps you on time. And part of that is sleep. So when you go to bed and when you wake up, and when you’re hungry, and when you like to move and when you don’t like to move, and many things actually influence that.
So parts of circadian rhythm, they just control themselves. That’s this part of this timekeeper in your brain. But then there’s a lot of external influences. A big one is light. So your eyes see light, tells your brain it’s daytime. And that is something that sort of resets that timekeeper each day. Scientists call that a zeitgeber. It’s a fancy word that means it’s a cue. It’s an external cue that tells your brain, “Ah, your clock needs to reset and keep it on time.” So light’s really, really important. So aside from sleep, light is what tells your brain and your body how things should work at one time. So this gets into, like, shift work.
Gets into light pollution and gets into jet lag, because a lot of it has to do with your brain sensing light and what determines a day.
Kellams: You know, we read so much about how good sleep is important to our health. So circadian rhythms, I’m sure, are connected to our health.
Anthony: Sure. So part of circadian rhythms is sleep. Part of sleep is determined by light. So that’s a big influence. It’s a big cue that tells your brain and your body when to be awake and when to go to bed. There’s another really big cue that your body senses, and that’s food. So when you eat actually can be an even greater influence on your rhythms than light.
The best-case scenario is that your food intake is what we call aligned, is in kind of the right time frame as light. That’s the healthiest for your body. Those that are on shift work, and they are up all night and they sleep all day, and so their food intake is at night and they sleep during the day, these individuals are at a higher risk of chronic disease.
And part of that is because the two cues that help set their rhythms are what we call misaligned. They’re not happening when they should, at the same time, compatible with each other. So a lot of research is done to figure out why that is. Why, if your food intake and your light exposure are not properly aligned, how does that result in chronic disease? Because there’s a lot of people, between shift work and jet lag, have to suffer potentially health consequences.
Baum: So I have a question. Is there a way to tell how to align our food intake with light? Right now, our society’s preprogrammed to eat breakfast, lunch and dinner, or like at school or whatever, before set times in the day. But do we know, is it known, or is this what you’re trying to figure out, like when those food eating occasions should happen within light?
Anthony: So as humans, we are up during the day and we sleep at night. We’re diurnal. And so the idea is that most of your food intake happening during that light active time is because it is aligned with circadian rhythms. Why it would be unhealthy when you don’t eat it during that time has to do with brain mechanisms that interact with hormones. And so having food intake at a time in which your body systems are not used to assimilating food can result in a hormone balance which is quite different and also misaligned with our bodies.
So I think that the advice about eating three meals and during the day, and even sort of like old wives’ tales and coming from an agricultural society and up early, this is all sort of rooted almost innately in when is the healthiest time to eat. And it’s only through modern society, the ability to have electricity, lights all night, be able to have shift work, that we’re beginning to understand why that’s healthy.
Kellams: Yeah. Because I guess before electricity, before really shift work and those things, we were just sort of, what we did was mandated by the sun.
Anthony: Exactly, exactly. I mean, humans today have the least sleep probably in our history. Since the advent of electricity and being able to have more and more artificial light, humans have had progressively less and less sleep. And that alone goes along with chronic disease incidence.
Kellams: Can what we put in our body affect our circadian rhythms?
Anthony: Right. So there is quite a bit of research ongoing that has to do with food time. But then when it comes to type of food, there’s a bit of research on the role of all the different components of food, so like the macronutrients, carbohydrates, lipids, proteins. And there’s a bit of work that looks at diet quality. Some of the work that my lab does actually looks at protein quality as an independent regulator of circadian rhythms.
And it’s really interesting that not only just the time in which you eat something, but also what you eat, in fact, can have tiny influences even in a single meal. And what we’re finding is that those tiny influences quickly do get adjusted. We have systems in place which are really important for what we call maintaining homeostasis, keeping everything back on balance. And so meal to meal, we do see small changes, but they can be adjusted as long as we have these kinds of systems in place to handle it.
Baum: So as we approach shorter days, I’m one of those people, as soon as it’s dark out, I’m not leaving my house unless there’s a lot of reward involved. But what about, are there physical exercises people can do or things people can eat to kind of help keep their clock, their circadian rhythm, on track, or to help keep them going through these winter months? Has any research been done on that?
Anthony: Well, I think that if we just start with light, most of the research would say trying to have a routine of keeping yourself on your routine, and when you wake up, to try to get exposed to light so that that would set your day. For those that are particularly sensitive, there’s light boxes. But I think in general, having light exposure early in the day is one great way to.
And then also during the end of the day, you don’t want to have a lot of light, blue light, facing you. That’s what leads to hard to get to sleep. I mean, this even gets to daylight savings time, when to choose, fall back, spring forward. We’re going to be coming up on fall back pretty soon. Halloween coming up.
Buam: Is there any superfood or physical activity we can use to reset our clock?
Anthony: Yeah. Well, so I’ll say this about exercise. There was a paper that just came out recently that was in, I think, Nature Communications that looked at exercise timing in relation to sleep. And they looked at having that workout be within four hours of the time to go to bed.
And it appeared that the higher the intensity of the exercise, you really needed to keep that further away from your bedtime. The closer you worked out to the time you go to bed, the higher the intensity of the workout would make that a little more difficult to fall asleep.
Baum: One quick thing, when you mentioned jet lag, because even with the time change, I feel like the older I get, I’m sensitive to that one hour. Are there things we can do to help recover from that or reset our clocks quicker? Like things we can eat, things we can... Any best practices that help get us back on track faster?
Anthony: Yeah. I think that in terms of trying to help you with that adjustment, there’s a lot of techniques in terms of just ahead of time, trying to go to bed a few minutes earlier each day. I will say that it takes the body about a day to adjust to an hour. And this is true even in experimental animals. Every hour that you shift, it takes about a day to recover. So if you’re going six hours flying, it’s going to take you almost a week to kind of feel like totally you again.
So for example, I think you might have heard the NFL teams that went over to Melbourne, Australia. They practice circadian medicine. So they kept their team on the same time zone so that they would not have a delay in their performance. So you’re seeing that this is real science that people are realizing actually affects performance, and athletic performance, big money, big business, to try to prevent what you’re saying.
So is there things you can eat? I would say that good-quality food, good-quality protein, not processed food, not high-fat food. The types of compositional effects that have shown to shift rhythms have to do with sort of like really high-fat food, protein-imbalanced food. So keeping a good-quality diet during these times of change, I would say, has good data behind it.
Tracy Anthony is professor of nutritional science at Rutgers University and was on the University of Arkansas campus this week for a conference. My co-host for our series Balance is Jamie Baum, an associate professor in the University of Arkansas Department of Food Science and director of the Center for Human Nutrition at the UofA.
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