Nearly half of American adults say they rarely — or never — get a good night's sleep, according to a poll by the National Sleep Foundation. Sleep researchers Charles Czeisler and Scott Huettel discuss how sleep deprivation affects the brain, and why bedtime technology use may be partly to blame.
JOE PALCA, host: This is SCIENCE FRIDAY, and I'm Joe Palca.</s>JOE PALCA, host: Did you know that 250,000 people fall asleep at the wheel every day? A quarter of a million people? Why can't we get enough sleep to stay awake during a life-and-death activity?</s>JOE PALCA, host: Well, a new poll by the National Sleep Foundation suggests one of the things keeping us up at night may be our smartphones, our laptops, our TVs, all that technology in the bedroom keeping us mentally engaged until later in the evening. Got to finish that episode, right?</s>JOE PALCA, host: And those devices may be impacting the chemistry of our brains, too, by exposing to the bright lights of those screens at nighttime, sort of pressing the reset switch on our sleep cycle.</s>JOE PALCA, host: The question is what to do about it, how to get more sleep, especially as you age, and your brain isn't as easily lulled into a nice snooze. And what about a midday siesta?</s>JOE PALCA, host: Well, those were questions that were raised in this poll, but there's also an interesting question that we're going to start with, and that is why skipping sleep may give you a more optimistic outlook on life. And that's from an article that appears in this week's Journal of Neuroscience.</s>JOE PALCA, host: The other is Scott Huettel. He's an associate professor of psychology and neuroscience at Duke University in Durham, North Carolina, sorry. It's somewhere out there. And he joins us by phone. Welcome to SCIENCE FRIDAY, Dr. Huettel.</s>Dr. SCOTT HUETTEL (Duke University): Thank you for having me.</s>JOE PALCA, host: So you were looking at a particular behavior in sleep-deprived people. What were you looking at?</s>Dr. SCOTT HUETTEL (Duke University): Well, our participants come to the laboratory either after a normal night's sleep or after a night in which we've kept them up, and so they're not able to sleep normally.</s>Dr. SCOTT HUETTEL (Duke University): And what we do is, we put them into an MRI scanner, and we monitor brain activation while they make a series of choices in an economic gambling game. You can roughly think of it as chances where they can place their bets to win money or lose money.</s>Dr. SCOTT HUETTEL (Duke University): And what we found was that people changed their preferences. They changed the way in which they approached the decision problem, such as they're more likely to weigh the positive outcomes heavily. They're more likely to bet on good outcomes.</s>Dr. SCOTT HUETTEL (Duke University): And they actually downplay the chances of negative outcomes. They're basically - they're less loss-averse and more gain-seeking.</s>JOE PALCA, host: I see - okay, go ahead, I'm sorry.</s>Dr. SCOTT HUETTEL (Duke University): And what we found that was sort of striking, was that the brain regions that we know from previous research actually shaped this gain-seeking or loss-minimizing behavior are respectively amplified. People's brain regions are more responsive to gains. And the normal loss aversion response is actually pretty much abolished.</s>JOE PALCA, host: Really. So how is this related - I mean, what is it about missing sleep that's going to have this kind of effect on these centers in the brain?</s>Dr. SCOTT HUETTEL (Duke University): Well, one thing we know it's not, is it's not actually people just becoming less attentive because we can independently measure how attentive people are or how likely they are to sort of have lapses of attention. And that actually isn't predictive of how their behavior changed.</s>Dr. SCOTT HUETTEL (Duke University): What we found is there's indications they're becoming a little myopic. That is, they're narrowing down on a smaller set of possible outcomes and not thinking as broadly about the decision problem.</s>JOE PALCA, host: If you'd like to talk to us about sleep deprivation and some of the things it causes, you can call us at 800-989-8255. That's 800-989-TALK. We're talking with Dr. Scott Huettel. He's an associate professor of psychology and neuroscience at Duke University.</s>JOE PALCA, host: So I'm guessing that there's some real-world implications of this finding. You must have thought about those.</s>Dr. SCOTT HUETTEL (Duke University): Yeah, one of the ones that's most, perhaps disconcerting, is to think about - think about a doctor who has to make, of course, many types of decisions that often involve weighing, say, potential good outcomes and potential bad outcomes.</s>Dr. SCOTT HUETTEL (Duke University): Now, we naturally think that when doctors are sleep-deprived, we can do things that ameliorate their attentional deficits. So for example, they can take stimulants like caffeine, or they can just spend a little more time when they're making difficult decisions.</s>Dr. SCOTT HUETTEL (Duke University): And what our results suggest is that, in fact, those may help improve their attention, but that wouldn't be sufficient for getting rid of this optimism bias, where they would be more heavily weighing the good information and less attentive to the bad information.</s>JOE PALCA, host: I'd like to welcome another guest onto the show, right now. He's Dr. Charles Czeisler, the Baldino Professor of Sleep Medicine at Harvard Medical School in Boston. He's also chief of the Division of Sleep Medicine at Brigham and Women's Hospital there. And Dr. Czeisler was one of the authors of this new - or the description of this new poll that was done by the Sleep Federation. Welcome to the show, Dr. Czeisler.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Hi, Joe, thank you.</s>JOE PALCA, host: So how big a problem - we've just been talking about sleep deprivation. I know it's something that you've thought a lot. How big a problem is sleep deprivation in the American public from this poll that you've just completed?</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): It's a huge problem. And most Americans report that they don't get enough sleep at night. They don't feel refreshed in the morning. And they report a variety of negative outcomes, including adverse effects on mood, adverse effects on family life, social life, school, work, performance.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): And 66 percent of drivers under 30 admit to driving drowsy, 50 percent within the past month. As you mentioned, 250,000 people a day fall asleep at the wheel in the United States. It's a pervasive problem.</s>JOE PALCA, host: I see. And it's interesting. Now, we've just been hearing from Dr. Huettel about this notion that you'd be more risk-seeking if you're sleep deprived, and I'm just wondering if that could be linked to drivers being more aggressive or more likely to try to cut - you know, get in front of somebody with a slim margin because they're in this sleep-deprived state.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Yes, we know that people become fast and sloppy when they are sleep deprived so that instead of trying to preserve accuracy by slowing down, they'll keep going just as fast, even though they have - make more mistakes.</s>JOE PALCA, host: Well, if you have questions about not getting enough sleep or even about getting too much sleep, call us at 800-989-8255. And let's go to our first call now, and go to Hogan(ph) in Sacramento. Welcome to SCIENCE FRIDAY. You're on the air.</s>HOGAN (Caller): Hello. Yeah, I had a quick question about sleep. I'm a 27-year-old who cares for his 92-year-old grandfather, who's recently - his health has deteriorated. And what this has meant is that my sleep has been incredibly drastically affected, where maybe I'm getting six to seven hours of sleep, tops.</s>HOGAN (Caller): But more severely than that, my sleep is just constantly interrupted. Like maybe I'm getting up every hour, sometimes several times in an hour. And I've heard differing things about the effect of lack of REM sleep on your functioning. And I was just curious about any results of the studies or just generally your knowledge about what the lack of REM sleep does to you.</s>JOE PALCA, host: Dr. Czeisler, maybe you want to tackle that one?</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Well, first of all, the many interruptions of sleep that you're experiencing, as you do this important work for your grandfather, is going to affect your daytime performance. It's going to increase the risk of having lapses of attention and falling asleep, for example, at the wheel or being impaired in your work.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Interruptions of sleep, in and of themselves, can adversely affect the restorative value of sleep, even if you get the same amount of sleep. And the loss of rapid eye movement sleep can adversely affect your ability to solve problems, for example.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): It seems that during rapid eye movement sleep, we're integrating the experiences that we've had during the day and helping to solve problems and understand the way the world works in a way that we don't get from other stages of sleep or from trying to analyze the problem when we're awake.</s>JOE PALCA, host: Okay, let's take another call now and go to - let's see. We've got Tyson(ph) in Ann Arbor, Michigan. Tyson, welcome to SCIENCE FRIDAY.</s>TYSON (Caller): Hi, thanks for taking my call.</s>JOE PALCA, host: You bet.</s>TYSON (Caller): I was just in a psychology course, and they were talking about how an alternative therapy to depression is by skipping a night of sleep and how apparently that's one of the most effective ways to, like, instantly get rid of depression, which seems kind of related, right - the idea that we would become more positive with less sleep.</s>JOE PALCA, host: Interesting question. Dr. Huettel, what do you make of that?</s>Dr. SCOTT HUETTEL (Duke University): So I think that our results would be consistent with that, in that what we effectively show is that after sleep deprivation, some of the brain regions that are most important for responding to positive outcomes become more responsive. And similarly, those regions that are more important for dealing with negative, aversive or risky outcomes are less responsive.</s>Dr. SCOTT HUETTEL (Duke University): One thing, of course, to emphasize is that these are not panaceas in that there's many, as just was mentioned, many negative consequences that would probably have long-term effects on somebody's ability to do their job or interact with others that would probably, if this was repeated, counteract any immediate positive effects.</s>JOE PALCA, host: So if you're seriously sleep deprived, is it best to, like, catch a short nap, or do you really need to stop and get eight hours of sleep, Dr. Huettel?</s>Dr. SCOTT HUETTEL (Duke University): Well, I think that my understanding is that these both will help. One of the key things that is shown, is that there is levels of deprivation, and different individuals have different tolerances. So we know that after extended deprivation, essentially everyone's affected, but the individual variation of how much sleep is necessary means that some people may have - may better benefit from either of those two options.</s>JOE PALCA, host: Dr. Czeisler, is that your take on this, as well?</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Yes, and I think it's important to recognize, in terms of the effect on sleep loss on mood, that whereas there's a euphoria associated with acute sleep deprivation, as has just been described, and people sometimes feel punchy or slap-happy after they have been sleep deprived, and it can transiently be effective in reversing depressed mood, that chronic sleep loss has opposite effect. And people become burned out and have actually a higher risk for depression when they're chronically sleep-deprived.</s>JOE PALCA, host: Okay. Interesting. Let's go now to Dee(ph) in Gainesville. Dee, are you there in Gainesville, Florida?</s>DEE (Caller): Yeah, I am. Hi.</s>JOE PALCA, host: Hi. How are you? Give us your question.</s>DEE (Caller): All right. My question is how much is too much sleep? I go through having, like, maybe eight or nine hours of sleep a night to, like, maybe five. I mean, is there a limit to how much I should sleep to be able to function correctly during the day? I don't know...</s>JOE PALCA, host: I'm not sure...</s>DEE (Caller): ...what is...</s>JOE PALCA, host: I'm not sure it is 100 percent appropriate. But how old are you? I think that might relate to the answer to the question.</s>DEE (Caller): I'm 20 years old.</s>JOE PALCA, host: Okay. Apologies for being ageist, but it does play a role in this answer, Dr. Czeisler.</s>DEE (Caller): No problem.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Well, it does turn out that a lot of us, particularly when you describe that you're getting four, five hours a night of sleep per night on some nights, you begin to build up a sleep deficiency. And as that sleep deficiency builds, then you need a time to, sort of, recover that lost sleep.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): And there was an interesting experiment done a number of years ago at the National Institute of Mental Health in Bethesda by Dr. Tom Wehr in which he had people spend 14 hours a day - or a night in bed for a month. In the first week, they were sleeping 12, 12 and a half hours per night. And then it gradually dropped down, the next week, 10 or 11 hours and so on. Until finally, after they paid back this enormous sleep deficiency of about 32 hours, they finally settled down to about 8.2 to 8.3 hours of sleep per night.</s>DEE (Caller): That's interesting.</s>JOE PALCA, host: It is. This whole business about - I have to say, my son, who's 16, managed to oversleep by six and a half hours the other week. And so I'm completely stunned at his ability both - I don't know when he went to bed. So maybe he was up until four in the morning. But six and half hours oversleeping was pretty remarkable to me.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): As we get older, we can't do that anymore so...</s>JOE PALCA, host: Why is that? Why is it harder to sleep longer when you get older?</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Well, the depth of sleep is - we don't sleep as deeply when we get older, and we have many fewer - many more interruptions of sleep. We also have a much higher prevalence of sleep disorders. But setting the disorders aside, even when we study healthy, older people who do not have a sleep disorder, there's a much narrower window within the daily cycle at which they can maintain a consolidated bout of sleep. So it just we - we just can't sleep in until 2 o'clock in the afternoon typically when we're 70.</s>JOE PALCA, host: We're talking about sleep, sleep hygiene, sleep disorders, sleeping too much. I'm Joe Palca. And this is TALK OF THE NATION from SCIENCE FRIDAY.</s>JOE PALCA, host: Anyway, let's take another call now and go to Todd(ph) in - oops, sorry -Tony(ph) in Ann Arbor, Michigan. How are you?</s>TONY (Caller): Hi. I'm doing very well.</s>JOE PALCA, host: Great.</s>TONY (Caller): How are you?</s>JOE PALCA, host: I'm well. So what's your question?</s>TONY (Caller): I had a question about - is there any consideration to the role of pharmaceuticals meant to help sleep disorders as they're advertised on TV? I guess, they're supposed to work great. I don't know if I can say any of the products, but I'm sure we're aware of them. Do they affect the dream cycle? And do they, in process, keep affecting sleep deprivation or being able to come back and sleep normally?</s>JOE PALCA, host: Okay. Dr. Czeisler, I guess that's one for you.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): You know, many pharmaceutical products change the structure of sleep. So they may diminish the amount of deep, slow wave sleep, but increase the amount - the total duration of sleep, or some hasten the ability to fall asleep, but don't actually result in an increase in the total sleep duration.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): So there are different types of products. Some of the over-the-counter products might, you know, help us to fall asleep for a couple of days. But then we build up tolerance to them and they no longer are effective, or we would have to have higher and higher doses to be effective. So there are a variety of different products out there but none that I know of that really induce the same kind of sleep that one would get, you know, for example, when you're 18 years old.</s>JOE PALCA, host: Dr. Huettel, you said earlier - we were talking earlier about whether there are any things you can do, pharmaceutical agents - are there any agents that people who are sleep-deprived can do that will right them and keep them on the right course, or is really the only thing a night - a good night sleep or at least a certain amount of sleep?</s>Dr. SCOTT HUETTEL (Duke University): Well, I think that the different agents are going to have different affects, so that one common thing that many of us do is to take stimulants. And a stimulant has the wonderful feature of speeding up some behaviors and speeding up the brain mechanisms that underlie those behaviors.</s>Dr. SCOTT HUETTEL (Duke University): Now, what that may end up doing is raise arousal levels and make you more effective to function in some circumstances. But as a number of studies recently, including ours, have shown that what that made, in fact, do is not change all behaviors. It can help you with, perhaps, keeping you awake and alert in some situations. But things like reasoning abilities, higher cognition and decision-making may be left unaffected.</s>JOE PALCA, host: So - I mean, is the bottom line here for you, in terms of functioning appropriately, get the right amount of sleep? Is that what you're saying, Dr. Huettel?</s>Dr. SCOTT HUETTEL (Duke University): Yeah, I think so. And that what we want to do is not only get the right amount of sleep but recognize that when we aren't able to do that because of the pressures on modern life, to understand that we can't just solve the problem by taking a stimulant or by just giving yourself a little more time to make a decision. We're going - we want to recognize that sleep deprivation has these pretty subtle effects that can change our cognition.</s>JOE PALCA, host: I see. Well, thank you very much, Dr. Huettel, for joining us and explaining about your study. That was a very interesting issue. And certainly -as we are talking about this, it's certainly one that people in Las Vegas are probably counting on to get people to behave a little less rationally than they might otherwise when they're gambling in the middle of the night and probably have been up for a while.</s>Dr. SCOTT HUETTEL (Duke University): Right, right. And, of course, there's lots of other ways they can take our money as well.</s>JOE PALCA, host: Okay. That's Dr. Scott Huettel. He's an associate professor of psychology and neuroscience at Duke University in Durham, North Carolina.</s>JOE PALCA, host: And, Dr. Czeisler, you're going to stay with us and talk some more about this sleep study that was just completed. This is like the 20th year the study has been conducted, right?</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): That's correct. The National Sleep Foundation has been doing -conducting this poll for 20 consecutive years. And this particular poll is focused on the technologies that have invaded the bedroom and are responsible for a lot of the sleep loss that Americans experience.</s>JOE PALCA, host: Okay. Well, we'll deconstruct that when we come back from this short break. We're talking with Dr. Charles Czeisler about sleep and sleeping and sleeping too much and not sleeping enough. So stay with us.</s>JOE PALCA, host: This is SCIENCE FRIDAY from NPR.</s>JOE PALCA, host: This is SCIENCE FRIDAY. I'm Joe Palca.</s>JOE PALCA, host: We're talking this hour about groggy Americans and what we can do to rest a little easier with - at night. My guest is Charles Czeisler. He's the Baldino professor of sleep medicine at Harvard Medical School in Boston. He's also chief of the division of sleep medicine at Brigham and Women's Hospital there.</s>JOE PALCA, host: And we were talking about this poll of American sleep. And this year's poll focused on devices that we sometimes bring into the bedroom. What are we talking about? What kind of devices are we talking about here?</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Well, the TV was the first device that invaded the bedroom. And 80 percent of Americans report that they watch TV in the hour before going to sleep. And we know, for example, that teenagers with a TV in the bedroom spend eight and a half hours a day on recreational media of one sort or another, and those without a TV in the bedroom spend five and a half hours a day. So it's taking an extra three hours a day in those kids who have a TV in the bedroom.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): And it's not just TVs anymore. That's how it started. And now people are bringing their cell phones. Four out of 10 Americans are bringing their cell phone into the bedroom. In fact, three out of four teenagers bring the cell phone with them to the bedroom. And many people keep it up during the night. So 25 percent of Americans leave the cell phones on all night. And about 20 percent of Americans under 30 are awoken at least a few nights a week by cell phone ringing, text messages, email coming through their cell phones.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): So we've gone to - we've brought things to another level. People are playing video games before going to bed. One out of five Americans are, you know, all hyped up on online gaming or some sort of Internet or other type of computer game in the hour before sleep.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): And a lot of these technologies have exposure to light associated with them, or the lights are on in the room as they're happening. And we know that that suppresses the release of the sleep-promoting hormone, melatonin, and shifts its release to a later hour, not just tonight, but the next night. So it's making it more difficult to fall asleep today, as well as tomorrow and the next day, because of the light exposure that is resetting our internal clock.</s>JOE PALCA, host: And so is the message here don't do that?</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Well, I mean if - only 35 percent of Americans report that they are getting enough sleep at night. They recognize that it's having bad effects and that they're not getting enough. 70 percent say their work schedules allow them to get enough sleep and their school schedules, but they - more than half of them aren't getting that sleep that they could get.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): And so then, when we look at why, it seems that the invasion of these technologies into the bedroom, they're so engaging and enticing that they, sort of, lock us in and get us going on some type of interactive activity or watching an exciting program, five - surfing 500 different cable channels. And the next thing you know, it's 2 o'clock in the morning.</s>JOE PALCA, host: Yep. There you go. Okay. Let's take a call now from Chris(ph) in Columbia, Maryland. Chris, welcome to SCIENCE FRIDAY.</s>CHRIS (Caller): Hey, how are you doing?</s>JOE PALCA, host: I'm good.</s>CHRIS (Caller): Yeah. I was calling about - I'm actually a combat veteran. I've been deployed two times to Iraq and once to Afghanistan. I just returned from Afghanistan in December, which was a pretty rough tour. But my question was - I know you're talking about sleep deprivation and some symptoms. I know one or -there's been times when I was in Afghanistan that I went days literally without sleep or maybe an hour here, an hour there.</s>CHRIS (Caller): And some of my symptoms were - like I actually started hyper-vigilance and seeing things that weren't there, like - I mean like crazy stuff, like a pink elephant or something. I'm like, whoa, whoa, what was that, you know, like when I kind of dozed off. And I'm wondering if, through your studies, have you seen symptoms like that from people who have been deprived over days at a time or people only got, you know, a couple of hours over two or three days?</s>JOE PALCA, host: Oh, Chris, thanks for that call. What do you think of that, Dr. Czeisler?</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Well, that can occur as our, sort of, dreaming stages begin to occur when we're awake, and we have more difficultly separating out the difference between what's happening in the here and now and what's happening -that might be happening if we were asleep. So it does appear that part of the brain can begin to initiate sleep while another part of the brain is still awake.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): And if you're driving a car and that happens, that might lead to a phenomenon that we call automatic behavior, in which you begin to forget or not remember how you got from point A to point B on the expressway. Or suddenly, you're trying to get into a house, and then you realize that it's not yours. These are the sorts of things that can happen when we are - when sleep pressure is high enough.</s>JOE PALCA, host: Interesting. Well, thanks for that call, Chris. Let's take another call now and go to Lee in Savannah, Georgia. Lee, welcome to SCIENCE FRIDAY. You're on the air.</s>LEE (Caller): Yes. My son, he started getting severe headaches when he was nine years old, and he is 13 now. He's been through all kinds of tests and all. And one of the symptoms from his headaches is he cannot sleep at night. He's been through several sleep studies.</s>LEE (Caller): They found, you know, this problem, that problem, and we've had a couple of surgeries such as tonsils and things like that. Nothing has seemed to help his headache.</s>CONAN: Let me see if Dr. Czeisler has any suggestions about that. I mean, it sounds like it's not a sleep-related problem so much as a medical problem that's affecting sleep.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Yeah. It's hard to know without a bit more information. But sometimes sleep disordered breathing or sleep apnea, which can sometimes happen with large tonsils, can lead to morning headaches. They wouldn't typically last all day, and sleep deprivation itself can be associated with an increased risk of headaches.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): But it sounds like the situation you were describing, the headaches may be the primary issue which are themselves interfering with sleep.</s>JOE PALCA, host: Right. Right. So what, I mean, is - this - as you said, this study has been going on for 20 years. What's changed over the last 20 years about American sleep habits? Is it mostly these new electronic devices in the bedroom?</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Well, Americans are sleeping less and less. And there has - and we know that the consequences of this chronic under-sleeping are on many different aspects of health and performance. So as sleep duration at night has been decreasing, we know that one of the physiological consequences of that is a change in the hormones that regulate appetite and regulate the metabolism of sugar.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): So we become less sensitive to insulin when we're chronically sleep deprived, and the hormones that regulate appetite are changed in a way that makes us crave more food and - particularly carbohydrate-rich foods. So as sleep duration has declined, there has been a concurrent increase in the waistline of Americans, as they have gained more and more weight.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): And there's now research suggesting that there may be a causal link between this reduction in sleep duration and the increase in weight gain, and of course that then increases the risk of illnesses like diabetes and sleep apnea, and so on. So besides those kinds of effects, chronic sleep deficiency increases the risk of adverse effects on the cardiovascular system.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): So blood pressure goes up when we don't get enough sleep, daytime blood pressure, as well as the risk of calcification of the coronary arteries increases in people who are not getting enough sleep. Even the immune system is adversely affected, so that people who chronically get an inadequate amount of sleep, for example, only have half the antibody response to a flu shot in the first week. And also, if they get exposed to the virus that causes the common cold, they'll be at several times greater risk of actually catching a cold.</s>JOE PALCA, host: I'm sorry, but as we - as you were talking about this, it just occurred to me that somebody somewhere is going to come up with the sleep diet, which is going to be, you know, an extra eight hours of sleep a day to lose weight rapidly. I hope that doesn't happen.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Well, the - as a way of preventing weight gain, I think that that would be - getting enough sleep could be the easiest way to begin to lose weight.</s>JOE PALCA, host: There you go. That one would probably go down easy. Okay. Let's take another call now and go to Chris in Evansville, Illinois. Chris, welcome to SCIENCE FRIDAY. You're on the air.</s>CHRIS (Caller): Thank you very much. I'm enjoying the subject. It's just funny your guest mentioned about diabetes. My wife and I - actually for six years (unintelligible) almost never got a full night's sleep because our oldest son is diabetic, so we're constantly getting up in the middle of the night to check him.</s>CHRIS (Caller): But we were also finding that we weren't getting enough sleep because we had a, you know, TV in the bedroom, and of course with satellite, you know, so many channels to choose from.</s>CHRIS (Caller): And after we realized, you know (unintelligible) don't have enough energy or anything, we finally disconnected the satellite box in the TV in our bedroom, and the shows that we would normally stay up watching, we actually started to DVR them and...</s>JOE PALCA, host: You mean record them, yeah.</s>CHRIS (Caller): Yes. And watch them much earlier and set ourselves - you know, kind of like you would do with your children, set ourselves a bedtime so that we could, even though it's interrupted, still get a lot more sleep. So we kind of disconnected the technology, so to speak, that was keeping us from sleeping as much as we could.</s>JOE PALCA, host: No, I like that because you're using technology to overcome technology. So that's good.</s>CHRIS (Caller): (Unintelligible)</s>JOE PALCA, host: It's very good. Chris, thanks for that. Is that - does that strike you as a good plan, Dr. Czeisler?</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): It does. In fact, I set my own cell phone to have a bedtime alarm in the evening so that it begins to alert me that it's time to wind things down and get ready for bed. And I find that to be very helpful.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): The - what the caller described is actually - it has been studied that the parents of children who have either a medical condition or some other condition that disturbs the child's sleep and therefore disturbs the parents' sleep, that those parents are at greater risks for medical problems as well as mental health problems in having to cope with the sleep interruption that's associated with raising such kids.</s>JOE PALCA, host: I see. So just - I mean, what are the rules? One of the best - people -everybody says, oh, I just wish I could get a good night's sleep. I just wish -I mean, is there a few straightforward things that people could do that would really help?</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): You know, there are some simple tips. First of all, having a cool, dark, quiet place to sleep; secondly, setting aside an adequate amount of time for sleep. So it takes eight to nine hours in bed to get enough sleep for the average adult. Teenagers need at least nine to 10 hours of sleep. So you got to figure out when you have to get up in the morning. They're getting up between six and 7 o'clock in the morning. So you've got to work backwards and say, okay, I've got to go to bed nine to 10 hours before that in order to get enough sleep; and then trying to have a regular schedule.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): So some people, you know, on the weekends they're up till 2:00, 3 o'clock in the morning, and then they're trying to go to bed at 10 o'clock at night on weeknights. So that's like traveling back and forth from London back to the East Coast every time you want to try to go to bed on a weeknight, and that's going to make it much more difficult to fall asleep at night. And people are going be tossing and turning and thinking they can't fall asleep because they're going to work the next day. It's actually because they're trying to make a trip that's equivalent to flying to London, and then they're suffering from social jetlag, as we call it.</s>JOE PALCA, host: Social jetlag, I like that.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): And so having a regular schedule will improve sleep and then getting all this technology out of the bedroom, as the last caller has described, so that - I mean, you'll find that these shows and games and so on are less enticing the next day when you have plenty of other things to do than they are in the evening. And so if you can actually get them out of the bedroom and not bring - amazingly, about a quarter of people or a third of the people are now using their cell phone as an alarm clock.</s>JOE PALCA, host: Hmm.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): And they're not necessarily switching into alarm clock-only mode. So now they are tied to having a cell phone there in order to get up in time for their morning and that begins to create a vicious cycle. Just get the cell phone, the charger, the video games, the laptops, all these things out of the bedroom so that it can be a sanctuary for sleep.</s>JOE PALCA, host: It sounds like a plan. Well, thanks for joining us on this topic, Dr. Czeisler. You know it's one that's close to my heart.</s>Dr. CHARLES CZEISLER (Harvard Medical School, Brigham and Women's Hospital): Thank you, Joe.</s>JOE PALCA, host: Charles Czeisler is the Baldino Professor of Sleep Medicine at Harvard Medical School in Boston. He's also a chief of the Division of Sleep Medicine at Brigham and Women's Hospital there.</s>JOE PALCA, host: I'm Joe Palca. And this is SCIENCE FRIDAY from NPR.