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Brian Lehrer: Brian Lehrer on WNYC, and now we turn to your sleep. Americans are sleeping less than ever, apparently, about an hour less than their grandparents and great grandparents did in the 1940s. And if one hour less doesn't sound like a big deal, they say it can have a big impact on health. Studies show that an out-of-sync circadian rhythm can raise the risk of anything from obesity, to heart disease, digestive disorders, to depression. Joining us now with the latest science on our internal clocks and how to use them to improve sleep and health is Lynne Peeples, science writer and author of a new book called The Inner Clock: Living in Sync with Our Circadian Rhythms. Lynne, thanks for joining us. Welcome to WNYC.

Lynne Peeples: Thanks for having me, Brian.

Brian Lehrer: We've all heard the term, but what's a circadian rhythm?

Lynne Peeples: Right. So, our bodies are filled with trillions of these tiny timekeepers, nearly every cell. So in your brain, in your bowels, your hair follicles, even the muscles of your legs, and these are all coordinating with each other and with the sun, ideally, to prime the body to do the right things at the right times. So whether that's sleep, but also when to metabolize, digest food, when to repair the body, fend off invading pathogens, when you're at your peak strength or speed to sprint away from an enemy. We evolved with these rhythms, and these are not precision timepieces, so that word "circadian," that actually in Latin is-- circa means around, and diem is day. Because of that, because our biology is not precisely 24 hours, to maintain that coordination between our clocks and the 24-hour earth day, we need regular re-calibration, and that's needing those cues, seeking those signals of light and dark, incoming food, and this is where we get into trouble.

Brian Lehrer: You describe that colorfully as-- that is the circadian rhythms as a symphony of miniature timepieces ticking throughout your body. And one really fascinating example that you give of this that I didn't know is that we've got rhythm from the hair follicles on our heads to the skin on our toes. And so, as one example, you write that facial hair in men grows fastest during the day, producing the proverbial five-o'clock shadow. There is no 05:00 AM shadow if a man shaves at night, you write.

Lynne Peeples: That's right.

Brian Lehrer: That's incredible. What if you're on an overnight night shift and you shave before you go to work? Is it because you're awake that the hair grows faster, or is it because it's daylight?

Lynne Peeples: Oh, that's a very good question. I mean, this is all about your circadian rhythms, right? And if we get into shift work, we get into a whole lot of other things, but likely, your circadian rhythms are disrupted, so, yes, maybe your growth may be a little unpredictable, to be honest.

Brian Lehrer: All right. Listeners, we can take your phone calls on this question because everybody or somebody you know has a sleep issue. So, is anyone listening out there getting good sleep? Maybe you've made changes to better align your lifestyle with your circadian rhythms, you want to report that story? What did you notice about what good quality of sleep did for you once you started getting it again, beyond just having good energy throughout the day, and maybe just kind of feeling good? Did it change your health in a significant way? Or if the opposite has been true for you, have you noticed the negative consequences of poor sleep? Help us report this story with your story at 212-433-WNYC. Call or text 212-433-9692 for Lynne Peeples, author now of The Inner Clock: Living in Sync with Our Circadian Rhythms. What's the most documented health effect of not getting enough sleep, and what does the science tell us is enough sleep?

Lynne Peeples: Well, the science suggests adults need between seven and nine hours of sleep. As you noted in the intro, we're not quite getting that anymore, and your sleep need changes throughout your life. Younger people, adolescents, actually need more sleep. And as I talk about in the book, this is a major issue from what I'm gathering from scientists, because we're forcing a lot of teenagers to get up really early for school, and they're not getting at all the amount of sleep they need. But, yes, both the lack of sleep, and then also associated with that is that circadian disruption, so these are two things. They're definitely linked, but circadian is beyond just sleep. It affects all the systems of the body.

We now are finding links between depression, that's probably a pretty well known one, linking that to seasonal affective disorder. But metabolic disease, I think that's an area of really strong research that has made these connections, because your metabolism, it's your liver, your gut, it's on a clock. If you are throwing food calories at it when it is not primed and ready to handle those calories, then it's going to throw your body out of whack, and your metabolism is going to potentially lead to a greater risk of developing diabetes, obesity. There's a lot of research on shift workers where this really comes into play.

Brian Lehrer: Like overnight workers?

Lynne Peeples: Yes. Right.

Brian Lehrer: I want to-- Before we take some of the zillions of calls that we're getting from our listeners, because, like I said, everybody has sleep issues, or most people have sleep issues. I just want to let people know and let you describe a little bit some of the really weird things you did to study up for this book. You spent 10 nights in a Cold War era bunker that you found on Airbnb, and you spent a different night in a sunflower field. Why in each case?

Lynne Peeples: Sure. The bunker, I was seeking a place where I could hide from any signals of the time of day, so daylight, clocks, other people. And, yes, I found this Airbnb. A guy had bought this from the government, cleared it out, souped it up into a very luxurious Airbnb, I must say. I hid in there, I set the LED lights to a dim red which-- that color least affects your circadian rhythms, as I learned. Then I decked myself out with devices. I wore sleep trackers, a heart rate monitor, temperature sensors all over my body, glucose monitor, light sensor, tracking all this data during those 10 nights as I filled my time juggling, trying to learn to play the harmonica, and things like that. And, yes, I experienced and then witnessed, based on the data, just how out of whack my clocks became, and I could feel it. It felt like jet lag, but to a much higher degree, and the data [crosstalk]--

Brian Lehrer: Crystal in Brooklyn, you're on WNYC. Hi.

Crystal: Hi. I'm curious if your author could tell us, why do some people fight so hard against their circadian rhythms? Like children who don't want to go to bed on time, and grownups who should know better that don't want to go to bed on time.

Lynne Peeples: I would say-- I mean, society has a lot of influence on our circadian rhythms, for good and bad. I can't speak exactly to children, but there's so many fun things to do to keep up, right? But as we get older and we're forced into these regimented schedules of school start times, which I mentioned earlier, or work start times, we're forced to, a lot of us, to live against our clocks. That is fundamentally part of the big, broader issue here, and why so many of us are getting less sleep, but it's also pointing to potential solutions. I mean, flexing work hours, for example, and having meetings in the middle of the day. This is something that a lot of advocate scientists pointed me to, that there's relatively a low-hanging fruit here to help flex the time people can go to bed and get up so they're more in tune with their clocks and can avoid using alarm clocks.

Brian Lehrer: But that's a structural set of fixes, which is certainly a good idea to treat people as humanely as possible by institutions, but are also some people just early birds and others night owls?

Lynne Peeples: Oh, yes, absolutely. All of us tick a little differently. Some of our clocks tick faster, some are slower, and so, yes, we have early birds, night owls, everywhere, everything in between. It's a lot of why we can't all be expected to follow the same schedule on a day to day basis.

Brian Lehrer: Ariana in Bergen County, you're on WNYC. Hi, Ariana.

Ariana: Hi. I have an eight-week-old, so I am in the throes of the newborn stage, the lack of sleep. I am a therapist who is also a night owl. I used to schedule most of my clients in the afternoons and evenings, and that works for me. But since I'm definitely attuned to my emotions now, and I see that on the days where he sleeps less, I am just not functioning as well, I'm more irritable, I'm even more anxious when it comes to him. As a first time mom, of course, the anxiety is there, but I definitely noticed big shifts in my mood and my ability to cope. And just in general, just being able to think through things, to have conversations with people, and just my cognition definitely declines.

Brian Lehrer: Any advice for her, Lynne?

Lynne Peeples: Oh, geez. Yes. I mean, that's a tough one, and you're probably speaking a similar story to a lot of people. I think we have to do what we can with our circumstances, and I think there are actually some tools, even a little-- This is not quite circadian rhythm science, but light can be used. The same blue light that can help set our circadian rhythms can also be used to energize and help our alertness and mood. So, just trying to get as much of that bright light during the day to kind of help you get through those tougher times.

Some interesting things came up in my research about infants and babies, and how trying to get them to develop their rhythms in a quicker and more robust way can then help you sleep. So, getting them to see the day/night cycle in light, in their meals, and even if you're bottle feeding the baby, this was really interesting. Like, your breast milk is very different in the morning versus the night. Night milk has more melatonin, morning milk has more cortisol. One tip for very busy parents that have plenty of other things to worry about is to label milk if you pump it, and feed that to the baby at the appropriate time to help them sleep through the night.

Brian Lehrer: Really?

Lynne Peeples: Yes.

Brian Lehrer: I've never heard that. That's fascinating. Ariana, I don't know if that's helpful to you, but I hope it's a little helpful to you.

Ariana: Thank you so much. Yes, I did notice that when I have the curtains open in the morning and I actually start to wake up, rather than kind of closing them and sleeping in, that that is actually better for me.

Lynne Peeples: Great.

Brian Lehrer: Thank you very much. Thanks for calling in. Good luck, and congratulations with that new baby. I've always wondered, Lynne, about the term "I slept like a baby", which meant I slept very-- I thought I slept like a baby, I woke up every two hours crying and demanding to be fed.

Lynne Peeples: Right. That's just not the appropriate term.

Brian Lehrer: How about Valerie in Westchester, who I think has an interesting relationship with sleep. Hi, Valerie, you're on WNYC.

Valerie: Hi. Hello, Brian. Good morning. I wanted to make a statement that I definitely notice a change in my sleep, the length of my sleep at the equinox, like when the seasons change significantly in the fall and in the spring. I definitely have to start adjusting to the darkening time right now, and I feel like I need to get into bed earlier. I didn't know if the researcher had information about that. But before I go, I also wanted to mention that I do elder care, and I notice my clients really kind of getting off their schedule or very unsettled at this time when it's-- especially in the fall when the light is darkening. Do you have any research on that?

Brian Lehrer: Lynne?

Lynne Peeples: Yes, really interesting. I'll address your first thing first, and that is, there is some research suggesting that we do naturally sleep a little longer in the shorter days of winter and fall than we do spring/summer. And of course, depending on your latitude-- We evolved at the equator, right? 12 hours of light, 12 hours of dark. But yes, there is some evidence that naturally, we adjust our sleeping a little bit across the year. And then as far as the elder care, yes, it's really fascinating about the seasonal changes, but it's not surprising. As we age, our circadian rhythms dampen, so we don't have that strong pulse throughout the day of sleeping through the night, being awake during the day. Although there is research now pointing with improving circadian hygiene and things like that, that we could actually improve that and help our long-term circadian health.

Having said that, yes, there's research like at nursing facilities where they really try to infuse those bright days and dark nights for residents, because often, they're not getting outside, and maybe don't have access to windows. So, using LED technology to kind of infuse that, and finding a lot better sleep and behavior among the residents.

Brian Lehrer: A listener writes, "I've never needed more than six hours of sleep. I'm a night owl, and since retiring, I go to sleep around 02:00 AM, but I always seem to wake up around 7:30 or 8:00. I never feel tired during the day, and rarely take naps. Am I harming myself?" Asks this listener.

Lynne Peeples: Good question, not a clear answer. There are some people, it is rare, that are short sleepers, that just naturally don't need as much sleep. I met one of them, he was actually a scientist, a very successful scientist perhaps because he had more hours of the day to get work done. I mean, it is rare, but yes, you're not necessarily harming yourself. I think everything is an average, these numbers we throw around, and so there's a wide range of the amount of sleep people need and when they need that sleep.

Brian Lehrer: In our last minute, maybe you can talk about light a little bit. Another text message says, "Can the guest speak about the effects of blue light and white light and overhead lights versus light at or below eye level?" Beyond that, I know somebody who, even in a dark room, sleeps with an eye mask on the theory that any light is bad for health during sleep. I see you have a chapter in the book titled "Goodbye Alarm Clock", and you boil it down to the right light at the right time. So, say whatever you want in our last minute about light and sleep.

Lynne Peeples: Yes. I mean, it's all about that contrast, so it's bright days, and that is primarily-- it's the full spectrum of light that our bodies evolved with. Blue light is very rich from the sun during the day, so you want to try to get your light to be rich in those wavelengths, and overheads are good-- Just fill your day with light. Then at night, turn all those lights off, dim those, especially those overhead lights, and try to get those blue wavelengths out of your lights. So, oranger hues, warmer lights, less of it. Just having that contrast in your day is going to help your rhythms.

Then the two other points to ditch the alarm clock that I think everybody should keep in mind-- So, that's contrast, and then there's constrict. Constrict the hours in the day that you eat. Stop eating three hours before you go to bed if you can, because that's definitely been shown to help your rhythms and your digestion. We didn't evolve to eat midnight snacks. Then finally, consistency. So eat, sleep, exercise, do all those things at the same times every day.

Brian Lehrer: And listen to The Brian Lehrer Show every morning from 10:00 until 12:00, and you will hear people like Lynne Peeples, science writer and author of the new book, The Inner Clock: Living in Sync with Our Circadian Rhythms. Thank you so much. This was really informative.

Lynne Peeples: Thank you for having me, Brian.

Brian Lehrer: And that's our show for today, produced by Mary Croke, Lisa Allison, Amina Srna, Carl Boisrond, and Esperanza Rosenbaum. Juliana Fonda at the audio controls. Stay tuned for All of It.

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