Sleep deprivation can cause serious health and cognitive problems in humans. In short, it can make us fat, sick and stupid. But why do humans need so much sleep? Science correspondent Miles O'Brien talks to scientists on the cutting edge of sleep research and asks if there's any way humans might evolve into getting by with less.
RAY SUAREZ: Now we turn to a story about the power of sleep and what it may do for you physically and intellectually. It's a question researchers have long explored.
NewsHour science correspondent Miles O'Brien gets a firsthand look at how some of our thinking on the subject may be changing.
MILES O’BRIEN: This is what your momma you all that stuff for, huh? In case you do a sleep study, make sure you clean behind those ears.
Now, this gives new meaning to the term power nap. And I am fairly certain it's not the best way to dress for some rest, but this is what scientists -- well, actually, their guinea pigs -- must do to try and answer a stubborn mystery: Why do we sleep?
ROBERT STICKGOLD, HarvardUniversity: The basic driving evolutionary pressure for sleep is still hotly debated, and I don't even know if we have discovered it yet.
MILES O’BRIEN: Robert Stickgold has as good a chance as anyone at finding the answer. He is a professor of psychiatry at HarvardMedicalSchool and a leading sleep researcher.
ROBERT STICKGOLD: On some level, you can summarize what we know about sleep functions now by saying that if you don't get enough sleep, you're going to end up fat, sick and stupid. And that just feels like something my mother used to say to me.
MILES O’BRIEN: But we have the science now to prove that?
ROBERT STICKGOLD: But now we have some science to say that that's really what's going on.
MILES O’BRIEN: Stickgold's primary focus is on dreams and how they may make us smarter. His experiment begins with a video game. I was told to find my way through this maze as fast as I could several times, not my specialty. And after a while, I got a little, well, game-sick.
MAN: There's something different about the way your brain is going to process information while you're asleep than if you stayed awake.
MILES O’BRIEN: OK. Yes. It does make you a little woozy, doesn't it?
But after working on this problem, it was time to get some rest. I didn't do that very well either. I barely drifted off. And when I tried my hand at the maze again, I was equally inept. But real subjects who fall fast asleep can get through the maze on average a minute faster after their nap and even better if they dreamed about it.
ROBERT STICKGOLD: It's really those who can be remembering and reporting dreaming about the task that seemed to be the ones who really show the biggest improvement.
MILES O’BRIEN: So, if you mull it over in the dream, you come out way ahead?
ROBERT STICKGOLD: Way ahead. And if you mull it over while you're just sitting there awake, you don't.
MILES O’BRIEN: When we sleep, our brains receive no outside input and that frees up circuits that stay busy when we are awake. So, we actually have more bandwidth for problem-solving when we are conked out.
ROBERT STICKGOLD: It seems like the brain has evolved sleep, maybe specifically for this purpose of giving it a chance to look at recently learned information and understand it differently.
MILES O’BRIEN: Could this be the main reason we sleep?
ROBERT STICKGOLD: It could be one of the main reasons.
MILES O’BRIEN: But these killer whales may suggest Dr. Stickgold is all wet.
UCLA psychiatry Professor Jerry Siegel, also a top sleep researcher, began studying them when this fellow, Nakau (ph), was born at SeaWorld in 2001. Siegel's colleagues watched the newborn for weeks and weeks, and he never went to sleep, not a wink.
JERRY SIEGEL, University of California, Los Angeles: The longest any human has ever been awake is 11 to 12 days, and it's a major task for them to stay up for that long, and all sorts of bad things start to happen.
But here you have an animal as part of its normal lifespan being continuously active for a month and, you know, perfectly healthy and growing.
MILES O’BRIEN: This got Dr. Siegel thinking about the other star attractions here. He wondered if dolphins might have the same sleep pattern.
Sure enough, he and his team learned the newborns stay awake for weeks. And when they do get some rest, dolphins sleep hemispherically, meaning on only one side of the brain at a time, allowing them to stay conscious and keep moving.
They're mammals. They're smart mammals with a big brain. This idea that somehow sleep allows us to reboot our brains would suggest that the bigger the brain, the more you need sleep.
JERRY SIEGEL: Right.
MILES O’BRIEN: Not so.
JERRY SIEGEL: Right. And that's a surprising observation, but it's clearly the case.
MILES O’BRIEN: Consider brown bats, not so brainy, and yet they log 20 hours of sleep a day, while elephants, with their large brains that never forget, sleep only four hours.
But the bats can gorge on an insect meals at dusk, while elephants graze for hours on end. Maybe young dolphins and whales remain awake because they are particularly vulnerable to predators, and marine mammals have to make a conscious effort to surface for air. Sleep is just too risky.
JERRY SIEGEL: It's highly maladaptive for most animals under most conditions to be active 24 hours a day, assuming they can satisfy their vital needs in less time than that.
MILES O’BRIEN: In other words, it doesn't pay to stay up around the clock.
JERRY SIEGEL: Right. I think, rather than saying sleep is -- waking is good, you have to really say both waking and sleep are good.
WOMAN: No, you don't need more sleep?
MILES O’BRIEN: You don't -- you're getting plenty of sleep, right?
WOMAN: You getting plenty of sleep? Are you getting plenty of sleep? Yes.
(LAUGHTER)
MILES O’BRIEN: So if sleep gives us a competitive edge, makes us smarter, or both, what happens if we don't get enough?
ROBERT STICKGOLD: It's not just memories that are affected. If you only get four hours of sleep a night, the amount of antibodies you produce against bacteria, against viruses, is dramatically reduced.
Your ability to process food is altered, so that you have a greater hunger the next day. You start to look pre-diabetic. You will start to put on weight. We do not know how much of the obesity epidemic we're seeing in this country is in fact due to restricted sleep in the population nowadays. And there are cardiovascular implications for it.
MILES O’BRIEN: So there is no way that we can train ourselves to cram in the benefits of sleep into the proverbial eight-hour of sleep in the six-hour bag?
ROBERT STICKGOLD: Trying to get eight hours of sleep from a six-hour night is like trying to get 2,000 calories out of 1,000-calorie meal by eating eat faster. It just won't work. I'm sorry.
MILES O’BRIEN: Oh, come on.
There has got to be a way.
JEROME MERCIER, Yoga Instructor: Bend the knees. Lift the arms.
MILES O’BRIEN: And that is what brought me here to a yoga class in Santa Monica.
JEROME MERCIER: Anchor your shoulders down the spine.
Now, we're just here to observe the body, to observe the mind and to feel the breath.
MILES O’BRIEN: Yoga instructor Jerome Mercier gave me a lesson in the art of meditation.
How does meditation compare to sleep? Is there any -- are there any similarities, or is it kind of the opposite of sleep in a way?
JEROME MERCIER: I would say it's the opposite of sleeping, because the mind is uncontrollable in sleep, which explains the crazy dreams that we might have, and it's a hyperactive mind, I think, when, in meditation, the mind is really on pause.
MILES O’BRIEN: I have got to say for somebody like me who has a busy mind, it's hard just to stop, isn't it?
JEROME MERCIER: It is really hard to stop the mind. It's a hard task, but you have to start somewhere in order to understand how you think and what life is really about.
MILES O’BRIEN: At the University of Wisconsin, psychology professor Richie Davidson studies the minds of the best mediators on the planet, including many Tibetan monks. He has scanned their brains when they were practicing so-called compassionate meditation, and they consistently emit unusually large amounts of high-frequency gamma waves, linked to learning and brain plasticity.
RICHIE DAVIDSON, University of Wisconsin-Madison: The mind of a mediator, you can think of as like a very still lake which doesn't have a lot of mind-wandering. It doesn't have a lot of rumination, so that when a stimulus occurs, it will be very well prepared to be attentive to it.
MILES O’BRIEN: So maybe we can evolve our way into needing less sleep, maybe.
Is it possible we could be in the process of shrinking our sleep time in an evolutionary sense, and if we could come back a million years from now, we wouldn't be sleeping at all?
JERRY SIEGEL: Sure, it's possible that, in a few million years, if there are still humans around, we will sleep less, or it may be that we will decide that we enjoy sleeping, and since we can accomplish all our vital tasks in less time as we become more and more efficient with more electronic gadgets and a higher-caloric-density food, we may decide that the thing to do is sleep more.
MILES O’BRIEN: In the meantime, maybe we should all take some lessons from the masters.
All right, Coco, let's take a nap, shall we? I have never slept with a dolphin before. You are beautiful. Can I get your number?
(LAUGHTER)
JEFFREY BROWN: Well, Miles did stay awake long enough to write a column wrapping up his reporting on sleep patterns. Plus, you can watch outtakes of him swimming with the dolphins. Find those on our home page.