Speaking of Psychology - Rethinking sleep and mental health, with Philip Gehrman, PhD

Episode Date: July 8, 2026

Too often, we treat sleep as something we can sacrifice when life gets busy. But a growing body of research finds that sleep is essential to both mental and physical health -- and that sleep problems can be a cause, not just a consequence, of conditions like depression and anxiety. Philip Gehrman, PhD, discusses what happens in the brain while we sleep; how insomnia and disrupted circadian rhythms affect mental health; why psychologists are paying more attention to sleep; and what all of us can do to get better, more restorative sleep. Learn more about your ad choices. Visit megaphone.fm/adchoices

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Too often, we treat sleep as a luxury rather than a necessity. It's something we sacrifice when life gets busy, but even as the world makes it harder to prioritize sleep, psychologists and other researchers are finding increasing evidence that sleep is critical to our mental and physical health. They're also finding that addressing sleep problems may be an effective and underused way to treat mental health disorders. So what exactly happens in the sleeping brain? Why does a bad night's sleep affect our mood so profoundly? How are sleep and circadian rhythms connected to mental health? What have researchers learned about using sleep-based interventions to treat mental health disorders?

And what can all of us do to get enough good quality sleep in a world that seems designed to disrupt it? Welcome to Speaking of Psychology, the flagship podcast of the American Psychological Association that examines the links between psychological science and everyday life. I'm Kim Mills. My guest today is Dr. Philip German, a professor of clinical psychology and psychiatry at the University of Pennsylvania, where he directs the sleep neurobiology and psychopathology lab. His research focuses on sleep, circadian rhythms, and mental health, including the role that sleep disturbances play in mental health disorders and the development of new treatments

for insomnia and other sleep problems. He has published extensively in leading academic journals, and his work has been covered in media outlets, including Time Magazine and The Washington Post. He recently spoke with APA's magazine Monitor on Psychology for an article on the New Science of Sleep. Dr. German, thank you for joining me today. Thanks so much for having me. Let's start with the big picture. Why is sleep so important for our health and our mental health and what's happening in the brain while we're asleep that helps us function while we're awake? The short answer is there's a lot. We know that sleep plays so many critical roles for healthy brain functioning. So it's tied to our motion regulations

abilities, it's tied even to the clearance of waste products from the brain. So there's just a lot happening during sleep that is critical for a healthy brain functioning. Now, sleep problems are often seen as a symptom of depression, anxiety, or other mental health disorders, but your research suggests that sleep can be a cause, not just a consequence of mental health problems. How has our understanding of the relationship between sleep and mental health changed in recent years? Yeah, this is something the sleep field has been trying to change for a very long time, because as you said, it's just been assumed by the mental health field that when people have insomnia, you don't really need to pay attention to the insomnia or the other sleep problems.

you just have to focus on their depression, on their anxiety, on their psychosis, whatever it may be. But there's now several dozen longitudinal studies showing that for people who don't meet the criteria for any mental health problems, if they have trouble sleeping, they're roughly two to three times more likely to go on to develop depression, anxiety, substance use disorder. So poor sleep can actually be a risk factor increasing vulnerability to poor mental health. And is that being taught in schools right now? Well, most mental health providers, regardless of discipline, get virtually no education about sleep in their graduate school curriculum, despite the fact that we spend a third of our lives doing it.

And so we're trying to increase the education that's out there. But unfortunately, most people just aren't getting much of anything. So what are the implications of this new research for psychologists and other mental health clinicians? It really opens up our toolbox for a range of different options. And so, you know, I'm always trying to teach mental health providers to pay attention to sleep, to listen to what their clients are telling them about their sleep and to try to figure out are their specific sleep disorders going on. And if there are, the good news is we have effective treatments for a number of them. So bringing that sleep focus in can take a more holistic approach to someone's mental health and provide access to a whole new set of techniques that they can bring to bear on treating someone's mental health problems. Now, you talked a little bit about how the brain sort of goes through a cleaning process while we sleep.

And I'm wondering, how does that relate to inflammation? in the body, something that we now know is the cause of numerous physical ailments. This has been a really hot area of research the last six or seven years in the field where it was discovered that it's during sleep, that waste products that just normally build up from waking brain function, it's during sleep that they're cleared away, in particular our deep sleep. And the waste product that has been studied the most is the protein beta amyloid, which is of course thought to play a role in risk for Alzheimer's disease. And so, for example, one night of total sleep deprivation in healthy individuals is associated with a 20% increase of this protein in the brain.

And so we're now thinking that chronically not getting a good night of sleep actually increases risk for dementia. Now, there is some evidence that inflammation may be one of the pathways for these associations. We know that difficulty sleeping is associated with increased inflammation, and so there's a lot of research. It's a very hot area of research right now. Well, let's talk about insomnia, which you just alluded to. How common is it and how does it affect people's mental health over time? Chronic insomnia, meaning someone who's been having insomnia for three months or longer, is about 10 to 15 percent of the U.S. population. but about another 25 to 35% of people experience bouts of insomnia here and there,

but maybe not continuous to the point where we would say, well, this is a chronic problem. So if you add those up, it's roughly a third to a half of U.S. adults are experiencing insomnia to at least some degree. It's a huge problem. And as far as the impact on mental health, I often say there's kind of two components to that. What is the next day effects? So when I ask people, when you have not had a good night asleep, how does that affect you during the day? And one of the most common things I hear is, I'm irritable, I'm grouchy. And so there's the toll that it takes on just how you feel the next day in terms of your

emotional and mental functioning, difficulty concentrating, attention, things like that. Then there's the chronic issues. As I mentioned before, the fact that chronic insomnia can increase the likelihood of the of developing new onset mental health conditions or worsening pre-existing conditions. So what effective treatments do we have right now for chronic insomnia? So there's two main evidence-based approaches. There is the medication approach. And I always say the pros and cons of the medications are pros. They're widely available. There's a number of them to choose from. Cons are, the average effects are quite small, we're quite modest.

And so people often say, well, I sleep a little bit better with the medication, but still not great, and their effects can wear off over time. As a psychologist, what I practice is cognitive behavioral therapy for insomnia, or what we call CBTI, for short, which has decades of clinical trials evidence backing up its efficacy. And it's a fairly short-term treatment, as far as psychotherapies go, typically six to eight sessions, where we're teaching, people, a variety of techniques, I call it sleep retraining. We're teaching people how to break the cycle of insomnia and retrain their body into a healthy pattern of sleep again. And the pros are a good success rate. The improvements are generally maintained over time. The main disadvantage is it's obviously more work than medications. It's very easy to pop a pill, but people have to invest the time and energy into doing CBTI. I want to talk

about one of the more surprising findings in sleep research, which is that sleep deprivation can sometimes have an antidepressant effect. This seems counterintuitive. Maybe you can tell us a little bit more about this research that you have conducted. So counterintuitive is exactly the word that I use. It is, to my knowledge, the only potentially beneficial effect of sleep deprivation. and sometimes we call therapeutic sleep deprivation or people have also used the term wake therapy which sounds not as bad as therapeutic sleep deprivation but there's decades of research showing

that one night of total sleep deprivation is associated with improvement of depression in about 50% of individuals and so prior to some of the newer research on things like ketamine, it was long been known as the fastest antidepressant response that we have. Now, the disadvantage of it is that typically when people go back to sleep, their depression returns. So it has very rapid effects, but not very sustained effects.

And you say it only happens to about 50% of people who are studied. So I'm wondering, what is the difference in these two cohorts? Yeah, and that's what research has been, including our own, has been trying to figure out, is how can we figure out who is going to respond to sleep deprivation and who isn't? And so we did some research looking for neuroimaging markers, and we found some patterns of connectivity in the brain that had some predictive ability to see who was going to do well. There's some theories out there that depending on people's biological rhythms,

that that might predict whether they respond. Subtypes of depression may respond better than others. And so it's still a bit of a mystery, but people have for years tried to figure out what's different about these people who respond. So it doesn't sound like something that your therapist will necessarily tell you to go home and stay up all night and you'll feel better, right? Absolutely. And I hope no one listening to this takes away that they should go home and sleep deprive themselves or slav or tell their patients to do that. Because when it is done, it's done in controlled, highly monitored settings. Now, your work focuses quite a bit on sleep and circadian rhythms. Can you explain for listeners what circadian rhythms are and why they matter for mental health? Circadian rhythms are the daily

approximately 24-hour rhythms in our body. And what we've learned is that just about everything in our biology follows a daily rhythm. So our body temperature has a very strong circadian or daily rhythm. The levels of the different hormones in our body cycle in a 24-hour rhythm. Even our DNA, about two-thirds of our genome, is transcribed in a circadian fashion. And we know the circadian rhythms are present in humans all the way down to single-celled organisms. So they're just a central aspect of life. And they really just help to keep our body in sync with the environment around us, but also what we call internally synchronized, meaning the different parts of our body are all in sync with each other. So we know that when people

have disturbed circadian rhythms, it can also be a risk factor for poor mental health. And one of the more common ways in which this happens is people who are night owls. It's 10 to 15% of the population is a night owl, and it's hard for them to fall asleep until later. at night, hard for them to wake up early in the morning, which is fine unless you have responsibilities that mean you have to be up early. Our culture does not revolve around the night schedule. So you have these night owls who are being forced to live on a morning person's schedule in that mismatch can have detrimental effects on our mental health. And of course, the same thing happens to people who work shifts. I mean, for years when I was a reporter, I was on a night shift,

I was on an overnight shift, and I felt crummy the whole time. I mean, can you reset your circadian rhythm? And if so, how long does it take to do that? Yeah, about almost one in four workers in the U.S. is a shift worker. It's a huge problem. And you're absolutely right. It just wrecks havoc on our circadian rhythms. A lot of people, if they come off the night shift and they kind of go back on a day's schedule,

you know, within a few weeks or so, sometimes even faster, their circadian rhythms will readjust to the day's schedule. However, there are some people, and these are some of the people I see in the sleep clinic where I practice, even years later, their bodies have not readjusted. They seem to get stuck on a night schedule. And so we're often using certain kind of treatment approaches to try to re-synchronize their rhythms to a day schedule. You know, I've met people who say that they're fine with five or six hours of sleep. And I've been reading lately that the whole, you know, you have to have seven to eight hours of sleep is being questioned.

Do we know what the optimal amount of sleep is for most human beings? It's a difficult question to answer for a couple of reasons. One, most of the research we have is based on people's reports of how many hours of sleep that they get. And we know that we're actually pretty bad at judging how much we've slept at night sometimes. But it is certainly the case that based on epidemiological. research and experimental research, that seven to eight hours seems to be optimal for most people, although some need less and some need more. But the other problem is that we've developed almost, I often say it's almost an obsessive focus on sleep quantity. Everybody, oh, how many hours

did you sleep last night? In my opinion, we don't pay enough attention to the quality of sleep that people are getting. And so you can get eight or nine hours of sleep at night, but if it's poor quality sleep, you're still not going to feel rested during the day. So it's a matter of finding the right combination of quantity and quality. We're going to take a short break. When we return, I'll talk with Dr. German about how consumer sleep trackers like aura rings and others are changing people's attitudes about what constitutes a good night's sleep. Nowadays, a lot of us have trackers that we wear all the time, whether it's or a ring or a watch or, you know, other electronics that will tell you how you're sleeping.

I know my ring has told me that I've had poor quality sleep some nights and I get up in the morning and I feel fine. So how are these devices changing how we approach sleep? Is it just making us anxious? For some people, absolutely. you know, one of the most common questions I get that I can't answer very well is how accurate are these devices. Because, you know, we've been using these devices for, I mean, I first got involved in sleep research in, I guess it was 1995, and we were already using these devices. But we use research-grade devices where there are published validation studies, the algorithms they're using to estimate sleep and wake are published, so we know exactly what they're doing.

What most people have is now this proliferation of these what we call consumer wearables, where the companies typically don't publish validation studies, they don't publish their algorithms, and of course they're always tweaking their algorithms. So we really don't know how accurate they are. What does seem to be the case for the consumer wearables is that they may have the same pattern as the research devices, which is that they tend to be more accurate in people. who sleep well. Because if you think about what happens when people have insomnia, I mean, one of the main sensors that these devices is using is they're measuring movement. Well, people

with insomnia lie awake in bed still, but still awake. And these devices tend to overestimate that as sleep. And that's, so the worst you sleep, probably the less accurate these devices are. And it, what drives me crazy, is when my clients come in and they say exactly what you say, you know, I thought I slept well last night, but my wearable said I did it. So therefore, I did not. And they treat it as absolute truth. And so I always tell people to take them with a grain of salt. And there certainly, there have been some published studies of what a colleague has termed orthosomnia, where people are developing insomnia because of wearing these devices. They're developing this obsessive focus on

their sleep, and it's actually making their sleep worse. So the techniques that you would be using in the lab that are very different from what you might get from a smart watch. I mean, how is it different what you're looking at from, you say, like, these rings and so forth, they're measuring whether you're moving or not. What are you doing that's different? Physically observing people sleeping in a lab, is that the difference? So when people come into the sleep lab, or I should say, we're doing this a lot in people's homes these days. My current studies are almost all happening in people's homes now where we're monitoring their brain activities, so they're EEG. One of things that's important differentiator is all the wearable devices, they're not actually measuring

sleep. They're measuring movement, heart rates, skin temperature, depending on what sensors they contain. And they're using that information to estimate sleep and wakefulness. The only way you can actually measure sleep directly is by measuring brain activity. And so when people come to the sleep lab or if we study them in the home, we're getting them wired up with all these electrodes to measure direct brain activity as a just more reliable indicator of what is going on with their sleep. Most people experience periods of poor sleep, at least occasionally. How can you tell the difference between a minor sleep problem and one where you should be seeking help? Probably the biggest factor is how long it's been going on.

I mean, like you said, we all have bouts of insomnia here and there. Sometimes I'll ask when I'm talking to an audience, I'll say, raise your hand if you've never had a bad night asleep. And no one ever raises their hand. Right. And so, you know, definitely I want to normalize that some bad nights here and there are completely normal. But when it's going on for weeks, turning into some months, and it's just not going away.

Maybe it's time to talk with someone about it, especially if it's really having a negative impact on someone's ability to function. Oftentimes when people come to see me in clinic, and I say, how long have you had insomnia? So it's been 20 years. It's been 10 years. And I'll say, well, why didn't you seek help sooner for this?

Right. And so I'd say, like, you don't have to seek help me, be after a week. But if it's been a month, two months, three months, it's probably time. Now, do people's circadian rhythms change naturally as we get older? I mean, I'm getting older myself and I can tell you I used to hate to get up at, you know, seven o'clock, six o'clock in the morning. And now that's, you know, that's a normal time for me. And I'm just wondering, is that common? Does that happen for people that their rhythms will change as they age? Absolutely. We all have, on average, a two to three hours.

shift later in our circadian rhythms during puberty. In fact, some people have even argued this is a marker of puberty, is that your circadian rhythms, we say it's a delay in our circadian rhythms. And so teens just have a natural tendency to be night owls because of this shift. And this has led to, a lot of people are familiar with kind of the push of a lot of school districts around the US to make high school start times later. it's because of this, there's a biological mismatch between their circadian rhythm

and their early school start times. The majority of people by early to mid-20s will have shifted somewhat earlier again, although some people will remain lifelong night owls. And then exactly what you're describing, Kim, is later in life there's a tendency to advance our rhythms. So our rhythms tend to shift earlier later in life. and not everyone, but we do have a greater tendency to be mourning people the older weekend.

Broadly speaking, do you have advice for our listeners to make sure that they've got healthy sleep habits? One of the biggest things I'm always trying to communicate is just making sleep a priority. I mean, people live busy lives and often sleep is the thing that gets squeezed out of their schedule. And so I think it's a matter of making sleep a priority. I mean, no one wants to live life feeling tired day after day because they're not getting a good night of sleep. So making it a priority. So you're at least giving yourself enough time in bed to get opportunity for sleep. Some of the other things I recommend as kind of a good starting point are regularity.

are circadian rhythms like regularity. And so sometimes I talk with people and there's sleep schedules all over the place. You know, one night they're going to bed at 10, the next night it's one in the morning, then it's 11, and then it's 9. And when our schedules are widely variable, it's hard for our rhythms to get really set

to anyone one good rhythm. So keeping a regular schedule. And probably the other thing I recommend the most common is not to chase sleep. And what I mean by that is, sleep is one of those things that, of course, the harder we try to make it happen,

the less likely it is to actually happen, which my patients say is one of the most frustrating things about having insomnia is that the more they try to sleep better, the worse their sleep actually gets. And so when people find themselves in bed unable to sleep, one of the worst things to do is to just lie there tossing and turning for long periods of time. It's frustrating, it's anxiety provoking, and it actually just makes it harder to sleep. So I always recommend if people find themselves in bed, tossing and turning, trying to sleep,

is to take a break, is to get up, ideally go to a whole other room, and engage in relaxing but not overly stimulating activities, until you feel ready to sleep again, but just to avoid those long periods of tossing and turning in bed. And if you get up in the middle of the night, are there certain things that you should or shouldn't do? It should be relaxing, but not, I often say, sometimes people will tell me,

well, I get up and I turn on the TV. I say, the very next thing I say, well, what are you watching? Because I can't tell you how many people have told me they watch the news when they can't sleep at night. Oh, no. Exactly. I say, and when you're done watching the news, do you feel like all is well with the world and you can relax and go to sleep? Or if people are going to pick up something to read. I say, well, don't read a suspenseful murder novel because then you're going to get sucked into it and not want to go to sleep. But it doesn't need to be boring either. Back when we used to have phone books, I would tell, I have clients sometimes say, oh, I read the phone book when I can't sleep. And I would say, that sounds horrible. And so it should be enjoyable. relaxing, but not stimulating.

So what got you into the field of sleep research? Was this me search for you? Do you have sleep problems? No, actually, people ask me that a lot. And I often say, you know, I'm not much of an athlete, but if sleeping were an Olympic sport, I think I could meddle. I'm generally a really good sleeper.

It actually came down to my undergraduate time. The university where I work now, Penn, is actually where I went to college. and my senior year, I took a class on sleep and circadian rhythms. And I was hooked. I just, I found the topic to be so interesting. I mean, back then, we knew a lot less than we know now. We've come quite a long way since then.

But then after I graduated, I managed to get a job as a research assistant in the sleep lab here at Penn before going on to graduate school. And so that really solidified my interest. And so I always tell my undergraduate students, they say, you never know what difference is, what a single class is going to spark in terms of your interest. And I'm certainly an example of that. So what's next? I mean, you've been studying sleep now for quite a while. I mean, what are the questions that you're still trying to answer? What are you working on now? The whole intersection of sleep and mental health was a very hot area of research in the 1980s, kind of 1990s. And it kind of died off to a certain extent because significant and vain, there were a lot of dead ends that hit. The case I'm trying to make is that our research tools and techniques are so much better now that the time is really ripe to kind of reinvigorate this. area of research. And there's even just a lot of low-hanging fruit that we can be doing that taps into a newer techniques, that taps into these changes of technology. I mean, the fact that we can now put devices on people, or give people devices to measure EEG in their home for

weeks on end. I mean, we just have so many tools that we did not have back then. And I think Now it's also, sleep is such a popular cultural topic these days. I also think the time is right to understand how can we incorporate an understanding of sleep into routine mental health care. And so I'm always trying to kind of talk with people about how can you be incorporating sleep focused assessment and treatment into your practice because there's just so many opportunities to do that and really improve people's lives. Well, Dr. German, I want to thank you for joining me today. This has been very interesting and I hope helpful to some of our listeners.

It's been my pleasure. Thanks for having me on. You can find previous episodes of Speaking of Psychology on our website at speakingofpsychology. Or on Apple, Spotify, YouTube, or wherever you get your podcasts. And if you like what you've heard, please follow us and leave a review. If you have comments or ideas for future episodes, you can email us at Speaking of Psychology at AP. p.org. Speaking of psychology is produced by Lee Winerman.

Thank you for listening. The American Psychological Association. I'm Kim Mills. Hey, y'all. It's Kelly Clarkson with Wayfair. Ever order furniture online and wonder what if? Like, what if it doesn't hold up? That sofa was four days old.

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