This episode of the “Sleep Review Conversations” podcast features Michael J. Breus, PhD, DABSM, discussing chronobiology and chronotypes.

Breus’ book is The Power of When: Discover Your Chronotype—and the Best Time to Eat Lunch, Ask for a Raise, Have Sex, Write a Novel, Take Your Meds, and More. His quiz can be found at

Hosted and produced by Rose Rimler, associate editor of Sleep Review

Run time: 30:38

Transcript Below

Rose Rimler, Sleep Review associate editor (RR): Hello and welcome. You’re listening to “Sleep Review Conversations,” a podcast by healthcare media company Allied 360. I’m Rose Rimler, associate editor of Sleep Review magazine and and I’m here with my guest, Michael J. Breus.

Dr Breus holds a PhD in clinical psychology from the University of Georgia. He is a diplomate of the American Board of Sleep Medicine and a fellow of The American Academy of Sleep Medicine, and is on the editorial board of Sleep Review magazine. He is on the clinical advisory board for The Dr. Oz Show and frequently appears on the show. He also writes for WebMD and is the author of three books: Good Night: The Sleep Doctor’s 4-Week Program to Better Sleep and Better Health, which is now available in paperback under the name Beauty Sleep; The Sleep Doctor’s Diet Plan: Lose Weight Through Better Sleep, and most recently he is the author of The Power of When: Discover Your Chronotype—and the Best Time to Eat Lunch, Ask for a Raise, Have Sex, Write a Novel, Take Your Meds, and More, which is what we’ll be focusing on today. Somehow he does all that and manages to get enough sleep. Welcome, Dr Breus.

Breus: Well, thanks for having me.

RR: Great, and today we’re going to talk about Dr Breus’ work in chronobiology or the study of circadian rhythms and their effect on human health and wellness, hopefully that’s a good summary.  SRCoversationsCover

Breus: Yup.

RR: Good. Specifically, we’ll be discussing the concept of chronotypes, which Dr Breus focuses on in The Power of When. So I thought, Dr Breus, to start off with, could you tell me a little bit about your clinical background and how you came to specialize in chronobiology.

Breus: Well, it’s interesting, so I have been a clinician my entire career. I started 17, almost 18 years ago now, and got board certified, and have been really day-to-day seeing patients for quite a long time. Throughout my career I had seen all kinds of patients. I think at one time I thought I might have seen all 88 sleep disorders; I don’t know if that’s actually possible or not, but it sure felt like it. I started to become interested in chronobiology actually at the beginning of my career, but I didn’t really have an opportunity to do much with it.

I was very fortunate, I had written several books, and this felt like a natural evolution for me because I had written a book about basically insomnia. I had written a book about how to manage your weight through better sleep. One of the things I realized talking with my patients is that there were a lot of people who had real difficulty with their chronorhythms. Historically I had learned about chronorhythms and that there were morning people and evening people, then over the course of time it appeared there was some research looking at people kind of in the middle. One of the things I noticed personally in my patient population was that insomnia, if you weren’t off on your chronotype, there appeared to be almost a 4th chronotype.

The goal of the book was really to number-one: get the public to really understand what are chronotypes and how can we use them in our lives. Then number-two, to understand that there were at least four different types. If you look in the literature, there are claims of anywhere from two to as high as seven different types of chronorhythms, and I’m not suggesting that all of those might be right. I’m just saying that in my clinical practice, I find that the three kind of known chronotypes in insomnia seemed to be the ones that filled my practice the most, and the ones that my patients had the most questions with.

It all kind of also culminated with a particular patient. I was seeing a patient about three years ago now. She came in and she was an insomnia patient. I was doing sleep restriction and stimulus control and cognitive behavioral therapy with her, and it wasn’t working. We went back kind of to the drawing board and I said, “Well, tell me what’s going on. How can I understand more about your situation?” She said, “You know Dr Breus, it’s not that I can’t fall asleep, and it’s not that I can’t stay asleep.” She said, “I go to sleep at the wrong times.” I said, “Really, tell me a little bit more about that.”

She said, “Well, it’s interesting. If I could just go to bed at 2 o’clock in the morning and wake up at 9 o’clock, my life would be fantastic.” I immediately assumed that she was phase delayed, delayed sleep phase syndrome, so I started thinking about that, and I said, “You know, I want to run an experiment.” I caller her boss and I said, “Hey, I’d like to see, would it be possible for her to come in about two hours later and stay about two hours later, so coming in around, I don’t know, 10:30-11, and staying till 6:30-7?” He said, “Well, to be honest with you, she’s about to be fired, so I’m happy to try something because I like her and I want to keep her, but her work product has gone down, she falls asleep in meetings, she can never get to work on time. It’s just I can’t keep somebody like that around.”

I was like, “Okay, I can appreciate and understand that.” We tried the experiment, and I called him up about seven days later and I said, “How is she doing?” and he said, “I don’t know what you did to her, but it’s like a miracle.” I was like, “Really? Tell me more.” He said, “She’s able to come to work exactly when we’ve asked her to, she participates in meetings, her work product has improved, it’s really fantastic. He said, “She’s going to be able to keep her job, we’re going to move her to this new schedule. Who knows, I might even have other employees that need this schedule.” I called her back to tell her the good news, and her husband got on the phone and he said, “I like my wife better now,” and I thought that was a really powerful statement. That was a really important thing for him to say to me.

I got her on the phone and I said, “You know, what have you noticed?” and she said, “Well, I feel like I have my own personal time zones,” is what she called it. I was like, “Okay, tell me more about that.” She said, “Now that I’m showing up at work later, I’ve noticed that there are certain times where I’m really good at writing things, and certain times where I’m really good at getting detail work done, and things like that.” I said, “You know, this reminds me of the literature that I had known about with chronorhythms and chronotherapy for a long time,” so I decided to dig back in.

Would you believe me? I found almost 400 studies looking at chronorhythms with all kinds of different activities, all kinds of different implications. I said, “You know what? Nobody’s really written a popular press book on something like this,” so I figured why not, I’d give it a shot. I wrote up a non-fiction book proposal, and was fortunate enough to get a book deal with Little Brown, and it’s really kind of taken off from there.

RR: Yeah, you mentioned that there is a lot of primary literature on the subject, but not a lot of literature or information out there necessarily for lay people. I wonder, do a lot of other psychologists and doctors who specialize in treating patients with sleep disorders, do they typically know about chronotypes, or do they study chronobiology as well?


Michael J. Breus, PhD, DABSM

Breus: Well, you know when you look at sleep specialists across the globe, I think it depends on your patient population. The truth of the matter is is that 95% of the patients that people see in clinic are either snoring or sleep apnea. The other 5% are usually kind of a mish-mosh of narcolepsy or periodic limb movements, restless leg, insomnia in many cases, and a small number of them can have chronobiology issues. The good news is is that all of us have taken the board exam, where it is a big part of the board exam, learning more about it.

The American Academy of Sleep Medicine has actually put forward some great position papers on how to treat delayed sleep phase and advance sleep phase, to try to move people kind of back to what we would consider to be the social norm. To be honest with you, I felt like if there was a way that we could get people to not have to move their chronorhythm, but to be able to maintain what is their genetically based chronorhythm, I wonder how much happier they would be and how much more effective they would be, and all of that.

I couldn’t find an assessment tool that I liked, and so I created my own. It’s not an assessment tool like, “I’m going to diagnose people,” with it. It’s much more of a tool whereas it’s a fun quiz that I can get people to take that will then start to go down the road of becoming more educated on the different chronotypes. It’s not the typical quiz that one would think of surrounding a chronotype. Usually you think of questions where it asks, “What time do you like to get up? What time do you want to go to bed?” I ask those questions, but I also ask a lot of personality-related questions, I ask a lot of behavior-related questions based on the literature that I’ve been able to review and come up with.

I’m able to put people into one of four buckets. I renamed the buckets from early bird and night owl and hummingbird and insomniac to ones that I thought people could identify with, and I also chose animals as archetypes that actually subsist in those types of schedules. Early bird turns into a lion. We know that lions usually have their kill in the early morning hours, by the afternoon they’ve gotten pretty lazy. Bears are kind of in the middle, they wake up with the sun and go to sleep with the moon. Wolves are much more nocturnal creatures, so they replace the night owls. Then I use dolphins to represent my insomnia population, which by the way is my specialty as a PhD. I chose dolphins because, as many folks out there know, dolphins sleep uni-hemispherically, so only half of their brain is asleep while the other half is awake and looking for predators. I felt like that was a good representation of a lot of my patients who feel like they never quite get to sleep.

Once you knew what your chronotype was, then I just started matching up your hormone levels. Hormones work on a very circadian cycle. We know almost exactly when your cortisol is going to be high, when your melatonin is going to be low, epinephrine, adrenaline, noradrenaline, the list goes on and on. Then what I decided to do was match activities with hormones when they were at their peak, or when you would need them most. I was able to discover approximately 50 different activities where there’s a particular time of day when all the hormones that you might need for that activity are exactly where you want them to be. This is all based on what time your body wants to wake up and go to sleep, or otherwise known as your chronotype.

It actually worked out great. I was very pleased with the way things worked out, and a lot of people are really responding to the book. We’ve had a lot of people say, “I no longer feel guilty for feeling tired at 8:30 at night,” because they’re a lion, they’re my early morning types and they’re up at 5:30. Then I’ve had a lot of people who are my wolves, my late night people, say, “Oh my gosh, thank goodness somebody recognizes that I’m a creative person, but I’m just not too creative at 9 o’clock in the morning.” It’s really been a lot of fun, I feel comfortable in saying that we’ve educated a lot of people, and hopefully people are starting to identify if they do have a chronobiology disruption, and how they might be able to work with that.

RR: Right, and I think it’s kind of fun for people to take the quiz, which is available online for free, and it’s in the book as well, and at the very least it will get people kind of thinking about the subject of when is the best time to go to sleep and to get up, and should they be napping or when should they be napping.

Breus: It is free, if you go to you can take it. There’s only so much I can evaluate with 30-something questions on the internet, so I wouldn’t say that it’s the most accurate that it could be, but I think over time we’ll be able to refine it and make it even better.


RR: You mentioned that you kind of found that people that you saw in your practice fell into these four types, the lion, wolf, bear, and then dolphin. Do you think that there are other chronotypes, or even among those four, do you think that there are types that sleep physicians and doctors that treat sleep disorders, are they more likely to see certain chronotypes, and are there even some in addition to those four that may be very rare, or at least rare to people in practice?

Breus: Well, you know there is a chronotype assessment tool that evaluates seven different chronotypes out there. I don’t disagree with it at all, I just found that it was easier to lump them into these four categories. If we wanted to continue to refine the categories, absolutely, I think there probably are more chronotypes. I do get the question from time to time, people say, “Well you told me that I’m a bear, but I like to stay up until 2 o’clock in the morning, I feel like I’m more like a wolf.” I think that hybrids do exist. I’ve found that there are some people who, while they generally speaking, are in the middle, in what we would historically call the hummingbird category, which I’m calling the bear category, they lean a little bit more towards a night owl or a wolf.

I think hybrids do exist. When you’re a sleep specialist, you just kind of never know what’s walking through the door. Again, most of us, we treat a lot of sleep apnea because that’s what the referrals are for, and that’s what’s bothering the bed partner. However, if you’re an insomnia specialist, which I am, as a clinical psychologist that’s one of the areas I decided to specialize in within sleep disorders, you will see these chronotypes in your practice. The question becomes, do you want to try to change them and kind of go against their genetics? Or do you want to let mother nature be and teach them how to work within their genetic profile?

It’s not just one gene, although we know that the clock genes, the PER3 gene in particular, is one that’s very strong in helping regulate morning-ness and evening-ness. If you comb through all the data, there are close to 80 different biomarkers out there that can help us learn more and more about morning-ness and evening-ness, and these types of propensities. I would say if you’re somebody who’s an insomnia specialist, yeah you’re going to see a bunch of different chrono-typical issues. Whereas if you really play more in the apnea, snoring world, it’s less likely.

RR: You mentioned the PER3 gene, and I’m curious, what’s the evidence that there’s a genetic basis here? On a personal note, I always have this lull in the afternoon, it’s really predictable. I’ll feel myself start to drag and I think, “I bet it’s about 3 o’clock,” and then I look at the clock and it’s in fact 3 o’clock, sometimes on the dot. My dad, who’s retired now, he was visiting recently, and every day he would excuse himself to go take a nap at about 3 o’clock. I wonder, is this something that can run in families, or do we have any evidence of that, do we know?

Breus: First of all, we’re talking about potentially two different things here. Getting tired at approximately 3 o’clock in the afternoon, that’s actually a temperature issue. We know that there is a slight core body temperature drop that occurs between 1 and 3 in the afternoon, and as many folks out there probably already know, that drop is consistent with a production of melatonin. The same core body temperature drop that occurs around 10:30, 11 o’clock at night, it occurs to a much smaller level between one and three in the afternoon, and therefore we know that there’s some melatonin production, which is partially why people are getting so sleepy.

What’s interesting though, is within that one to three in the afternoon, that can change pretty dramatically based on what I was talking about with your chronotype. When we look at the PER3 clock gene in particular, one of the things to remember is if you have a long PER3 gene, you’ll need at least seven hours of deep sleep to function, and you tend to be an early riser. Whereas if you have a short PER3 gene, you can get by on light or less sleep, and you tend to be a late riser. It’s likely that at least one of your parents may have actually had the same chronotype as you, or looking at your father, the timing of his nap may eventually affect you as well.

RR: Speaking of families and aging, do chronotypes change as we age? I think there is a lot of evidence that that’s true.

Breus: They sure do. I happen to have two teenagers, and my teenagers are night owls or wolves for sure. This is very characteristic of teenagers in general, we know that there is a biology which kind of swings them that way. That’s something that’s important to recognize, something that’s important for people to really sit back and say, “Hm, what’s going on?” It’s not that your kids are lazy, because they’re not. What they are, is they’re kids who have strong, strong biological forces going within them called hormones, and those hormones have a traumatic effect on their ability to fall asleep and stay asleep, and things like that. We know that, as adolescents, many adolescents are wolfish.

We know that itty bitty babies and in the toddler range, they’re more on the lions or the early bird side. Any parent out there can tell you, all of the sudden their kid is up at 5:30 and raring to go, that’s very different. Your chronotype appears to be set somewhere around the 18-20 year old range, and then it seems to stick there till you’re about 40, 45. Then we start to see differences occur. We know that delta sleep changes, especially for women around the age of 40, and we also know that people have a tendency to move towards lighter sleep. As my patients age, I find that they have more fallen to the insomnia, or what I call dolphin range and/or the lion or early bird range.

We also know that as we get older, we become more medically frail, we also have more medications on board. A lot of time these medications can also have a fair bit to do with our ability to wake up earlier or have more disrupted sleep.

RR: Right, and I wanted to ask you about the comorbidities. The advice in the book seems in general directed at relatively healthy people, and I wonder, is it also applicable to people with comorbidities like anxiety or depression, who might otherwise be prescribed medication for those conditions, or perhaps they were being kept awake by chronic pain or something more physical?

Breus: The book was absolutely designed for fairly straightforward, normal, healthy individuals. We do have a tendency though to see in my dolphin category, a fairly large number of them have a significant amount of anxiety, and sometimes that’s what’s driving their insomnia, that can be driving their poor sleep. We also know that there could be some genetics that are driving poor sleep. There is data to suggest that some people are actually born not-so-great sleepers, they have what we call “temperament issues,” they have stimulation issues in terms of they have a greater likelihood of being stimulated by stimulus that might not be stimulating to other people.

I think that people with anxiety do well with this book. They have a tendency to fall into the dolphin category, which is by design, and so I give them recommendations for sleep habits for things to do during the day. By and large, the dolphins, I’ve gotten a great response from my dolphins or my problem sleepers, and they have a tendency to respond quite well to the program.

Depression is different in a lot of ways. Sometimes I do find depression a lot more in my wolf category. My wolves are my introverts, they’re my creatives, they’re my actors, they’re my musicians, they’re my authors, people like that. They do have a tendency to have a little bit more depression, and it’s interesting because I think part of that could be fueled by their atypical chronotype of being a night owl. People think that night owls are lazy, people think that night owls are stand-offish and they’re introverted because they’ve been called all these different things their whole lives. I personally am a wolf, I have been my whole life. I’ve always been a night person, I rarely go to bed before 12, 12:30. I don’t require a tremendous amount of sleep, and so I’m up usually within six and a half to seven hours. I’m in bed at one, I’m out of bed by 7:30, if I’m in bed at 12, I’m out of bed at 6:30 type of thing.

It’s interesting when you look at mental health and chronotypes, but when you look at somebody who’s got issues with pain, this book is going to be hard for them to really have a whole lot to do with. Because in fact that pain is very disruptive to their sleep. I used to work in a pain center because people in pain don’t sleep and we know that their anxiety levels are quite high, but we also know that the pain is incredibly disruptive to their sleep cycle.

RR: It’s unfortunate that there’s so much guilt and anxiety just around whether or not you’re sleeping enough or at the right time, if you’re productive at the right time of day.

Breus: It’s so unfortunate because society seems to really kind of point the finger, and it’s like, “What? You’re not up before 10 o’clock? What’s wrong with you? Oh my gosh, you’re still working at 11 o’clock at night? You must be a bad parent or a bad partner, because all you’re doing is working.” People don’t get it, and I think part of the reasoning behind the book that’s important is for people to say, “Hey, you know what? It’s actually okay that you have a different kind of sleep pattern, and if you can get that sleep, you’re probably going to be in good shape.”

One of the questions I get asked all the time has to do with relationships, and what happens when you’ve got a couple and they are chrono-atypical? Where one person is a lion, a morning person, and one person is a wolf that’s a night owl, and actually I address that in the book. The book is really about communication, and the book is about learning what you are, and then helping other people understand it, so they can better understand you, and you can better understand them.

One of the chapters that most people like to talk about is the chapter on sex. When is the best time for sex? I actually created a matrix in the book to look at sexual desire. It turns out that 70-something percent of the time, most people have sex truly based on convenience and convenience only. It’s they’re lying there, the other person’s lying there, it’s late at night, it’s usually 11, 11:30. What’s fascinating is if you look at the hormones required for desirous sexual activity, they’re all low at 11:30 at night. Your estrogen is low, your progesterone is low, your testosterone is low, cortisol is low, and adrenaline is low. The one thing that you don’t want to have high is melatonin, and guess what? It’s pretty high around 10:30, 11 o’clock. It’s fascinating to me that that’s the choice, that’s the time that most people choose to have sex. One of the prescriptions if you will, not really a prescription but one of the pieces of advice from the book is try having sex on Saturday at 9 o’clock in the morning, and see if that works for you and your partner, you might really be surprised.

That’s the goal of the book is really to educate people on daily activities, and when might be their best time of day or their worst time of day, because communication really does turn out to be key.

RR: I wonder how that might change culturally in a different country or among a different culture.

Breus: It’s really interesting when you go to for example, Latin American countries where they have siestas, and you go to places like Denmark where they have very little sunlight during certain parts of the year. There’s cultural differences, there’s environmental differences. There’s a lot of things to think about, but the good news is that a lot of this is very applicable to people, and people are really getting a kick out of it, they’re having fun with it, and they’re learning something, which is my goal.

RR: Many of our readers and listeners are people who work in the field of sleep medicine, physicians, psychologists. What can you tell them about how to use this research, and when should they suspect a chronotype misalignment, or how should they use this information going forward?

Breus: First of all, just to be super clear, I didn’t do any of the research. What I did was I aggregated all of the research out there in a way, shape, and form that’s super easy for the lay person to understand and to take advantage of. I didn’t do any specific research or anything like that, but for all the folks out there number-one, feel free to get in touch with me, I’m always happy to answer questions and to help in any way that I can. Number-two, I think that in the insomnia group of patients, when you’ve got people who’ve got insomnia, this might be a really good way for them to help understand that if they are misaligned, if they are a night owl or an early bird and learning more about their day, I think it can be very helpful, in conjunction with a cognitive behavioral therapy program, in conjunction with supplementation, things of that nature.

RR: What kind of advice do you have for people whose career doesn’t quite match their chronotype?

Breus: There’s a lot of them. This also, by the way, falls in line with shift work as well. I have had a very large number of shift workers come to me after checking out the book and saying, “What do I do if I’m a shift worker?” because they’re chrono-misaligned no matter what. They’re working at night when they should be asleep, and asleep during the day when they should be working. There’s a lot of different ways to kind of look at it and work through it, but what I tell people is you’ve got to educate yourself first and really know and understand what the chronotype is that you are and that you’re dealing with in your family.

As an example, when I pick my daughter up, who’s classically a wolf, when I pick my daughter up from school at around 3 o’clock, she has almost no interest in speaking with me. I’m hopeful that it’s not me, but if I talk to her, like if I ask her, “How was school?” she’s like, “Fine.” I’ll say, “How was your classes?” “Fine,” but if I walk into her room at around 10 o’clock at night and I say, “How was school?” I could be there for 45 minutes. It’s great to be able to utilize this in my own personal world and be able to strengthen that bond with my daughter.

I think as sleep specialists and psychologists and people who are working with the sleep community, I think this is another great tool to learn from. What’s nice about it is it’s very readable and very actionable. It gives patients a plan. One section of the book says “A day in the life of a dolphin, or a bear, or a wolf, or a lion.” It actually lays out a schedule for people, and what it does is it emphasizes the underlying principles of consistency for circadian rhythms.

If people read the book and discover their chronotype, and if all they do is get their sleep schedules consistent, I have done a miraculous job at this point. Because we know that the average person doesn’t have a very consistent sleep schedule, and this is a great, fun, interesting way to go about doing it. You know, we as sleep specialists rarely talk about things like when should you go for a run, or when should you have sex, or when should you ask your boss for a raise. That’s all in the book, and it kind of widens our areas to be a little bit more accepted by patients, and for them to understand, “Hey, Dr Breus isn’t just trying to get you to go to sleep and wake up at the same time because he’s got nothing better to do with his time. It’s because it’s going to actually help you in a lot of ways, not just your sleep.

RR: Then finally, where do you recommend people go for more information? We’ll include a link to your book and to the quiz when we post the podcast, but I wonder if there’s any other resources you recommend in terms of books or even apps that can help people adjust their circadian rhythms.

Breus: First of all, from a sleep professional community, there’s always light therapy. The American Academy of Sleep Medicine (AASM) has done a wonderful job developing circadian rhythm treatment protocols that are available on the AASM website. The National Sleep Foundation has also done a wonderful job of helping describe chronotypes in a decent amount of detail for patients to get a little bit more information, or for professionals out there to get more information. I am happy to be a resource for people, if people want to contact me I am in the AASM directory. I’m happy to take calls or emails whenever.

For patients, if they want to just take the quiz because it’s fun and interesting, it’s at, and the book site is

RR: All right, well great. Is there anything else that you’d like to add?

Breus: No, just I appreciate the opportunity to talk with other colleagues about my work. It’s certainly fun and interesting, always up for feedback, things you like, things you don’t, things I might be able to change. Always interested in what people have to say, so thanks so much for the opportunity, and I really enjoy being a contributor to Sleep Review.

RR: Great, well Dr Breus, thank you so much for your insights on chronobiology and chronotypes and for discussing your book with me today.

Breus: Thank you.

RR: Thanks for listening to this episode of Sleep Review Conversations. Visit and click on “resources” for a transcript of this audio file as well as a link to Dr Breus’ chronotypes quiz.