The Science of Sleep


By Dan Gordon '85

Published Jul 1, 2018 8:00 AM

More than one-third of Americans are chronically sleep-deprived. UCLA researchers are at the leading edge of exploring the consequences and possible remedies.

Even when he was leading Britain to victory in World War II, Winston Churchill had to have his early afternoon naps. The snoozes were simply nonnegotiable. “Nature has not intended mankind to work from 8 in the morning until midnight without the refreshment of blessed oblivion which, even if it only lasts 20 minutes, is sufficient to renew all the vital forces,” he explained.

Today, some 75 years later, most of America’s work culture hasn’t caught on to Churchill’s wisdom. So we plow through, often at half speed, yearning to renew our vital forces but rarely doing so.

Just what are the consequences of chronically getting too little sleep? How can we ensure that we get more? What solutions does science offer?

Photo-Illustrations by Hugh Kretschmer


At UCLA, dozens of researchers are exploring questions about sleep and its relationship to health. “UCLA faculty are internationally recognized for leadership in sleep research and sleep medicine,” says Ralph Lydic, the University of Tennessee’s Robert H. Cole Professor of Neuroscience and a past president of the North American Sleep Research Society. Sleep is “a modifiable risk factor,” he says, enabling us to influence the divide between wellness and disease.

UCLA Chancellor Gene Block notes that aspects of modern life threaten to wreak havoc with our circadian rhythm — the sophisticated internal body clock that has evolved in humans and nearly all other living things in response to the 24-hour cycle of light and darkness. A leading expert in the neural mechanisms by which organisms adjust sleep and wakefulness to the day and night cycle, Block argues that recent developments such as international travel, more irregular work hours and mealtimes, and increased light exposure at night disrupt the body’s natural state of equilibrium.

“If you look at satellite photographs, it’s striking how much brighter the world is becoming as a result of how much more artificial lighting is used at night than in earlier times,” Block says. “And a lot of that is blue light, the wavelengths the biological clock system is most sensitive to.” Among other things, bright light inhibits the production of the sleep-promoting hormone melatonin, whose levels are otherwise intended to rise as darkness falls. To those who can’t avoid staring into electronic devices at night, Block recommends at least using the devices’ settings to dim the light emitted and shift it to warmer colors.


While occasionally knocking your internal clock out of sync might result in some unproductive afternoons, chronic disruption carries a heavier toll, including the potential for cognitive, cardiovascular and gastrointestinal problems. Block was involved in a study with other investigators at UCLA that showed that disrupted light schedules led to Type 2 diabetes in rat models.

At the minimum, many of us are almost always tired. On average, Americans today sleep an hour less per night than was the case in the 1940s, according to Gallup polling. While the average of 6.8 hours is just a catnap short of the 7-or-more recommended by the American Academy of Sleep Medicine for optimal health and wellbeing, the Centers for Disease Control and Prevention estimates that more than one-third of Americans regularly sleep too little. Nearly half of U.S. adults report that poor or insufficient sleep significantly impaired their daily activities at least once in the last week. Approximately 10 percent suffer from chronic insomnia, costing the U.S. economy an estimated $63 billion a year in lost work performance.

We all know about the irritability and lack of productivity we experience after a poor night’s sleep, but the price we pay for chronic sleep deficiency is much steeper than most of us realize — including a potentially increased risk for heart disease, high blood pressure, diabetes and certain cancers. In some cases, sleep difficulties act as an early warning that something is amiss. “People will live for years with a sleep problem without knowing anything is wrong, and only when it leads to other issues do they seek treatment,” says Alon Avidan ’88, director of the UCLA Sleep Disorders Center.

Chronic sleep deprivation suppresses the immune system and is even associated with a greater propensity toward weight gain and obesity. “When people are under psychological or physical stress, they are driven to eat more unhealthy foods,” says Paul Macey, an associate professor and sleep researcher in the UCLA School of Nursing. “If you feel refreshed from sleep, it becomes easier to motivate yourself to exercise and eat well.”


Poor sleep also weighs on the brain. It is closely linked with depression and anxiety, although whether it’s the poor sleep that brings on the mood symptoms or the opposite isn’t always clear. Researchers are also learning that sleep deprivation might increase the risk of neurological and psychiatric disorders, including Alzheimer’s disease — perhaps because one of sleep’s functions is believed to be the removal of toxins that accumulate in the brain and promote inflammation.

Last November, a group headed by neurosurgeon Itzhak Fried M.A. ’77, Ph.D. ’81 of UCLA’s David Geffen School of Medicine showed in vivid terms the impact of sleeplessness on our ability to perform mental tasks. Fried’s study looked at the effects of sleep deprivation on individual brain cells in 12 patients who, because they were preparing to undergo surgery for epilepsy, had electrodes implanted in their brains to pinpoint the origin of their seizures and were being kept awake to hasten the onset of an epileptic episode.

Researchers asked the patients to categorize images of faces, places and animals, setting off electrical activity in parts of the brain involved in perception. Four of the patients then sorted an additional set of images after staying up all night. In these patients, the speed and strength with which the brain cells fired declined precipitously, corresponding with their growing difficulty with the task. “It’s not just your motor abilities but your perception of the world that slows down when you are deprived of sleep,” Fried says.

The study serves up a detailed portrait of the mental lapses we experience after an all-nighter. While parts of the brain were running as usual, hallmarks of sleep took over in certain regions.

“We don’t have the same gravity of concern about people who drive while tired as we do about drunk drivers,” Fried says, “but the result can be similar.”


Our problem is as much with quality as quantity. An estimated 50 to 70 million Americans have chronic sleep disorders. This includes at least 25 million who suffer from obstructive sleep apnea, in which partially blocked airways in the back of the throat cause interrupted breathing throughout the night, resulting in excessive daytime sleepiness from the failure to experience sustained slumber. “Normal sleep goes through multiple stages, from light to deep and dream, or rapid eye movement, sleep,” Avidan says. “Medical issues such as obstructive sleep apnea fragment people’s sleep continuity, preventing them from entering those deep stages.”

Obstructive sleep apnea and other sleep-disordered breathing conditions are under-diagnosed, Avidan notes, particularly in people who don’t have a bed partner to point out the signs. Many assume that if they don’t fit the common profile — a middle-aged, obese male — they aren’t candidates, but females and young, non-overweight individuals are frequently diagnosed, as are children. Also, any noisy breathing during sleep, particularly when combined with daytime sleepiness, should be evaluated, Avidan says.

It was once widely believed that the worst consequences to not addressing the sleep-disordered breathing were struggles with alertness during the waking hours and perhaps an annoyed spouse at night. But a growing body of evidence, much of it contributed by UCLA researchers, is spelling out ominous health risks stemming from both the bouts of oxygen deprivation and the interrupted sleep. These include a propensity toward high blood pressure, diabetes, low testosterone, cardiovascular complications and stroke. About half of people with obstructive sleep apnea suffer from depression; many report problems with memory and decision-making, anxiety and stress.


The most effective treatment for sleep apnea is continuous positive airway pressure, or CPAP, which delivers steady air through a mask. But CPAP can be cumbersome, and many people fail to stick with it. Avidan says the problem with noncompliance is often an ill-fitting mask or incorrect usage. At the Sleep Disorders Center, he notes, sleep technologists work with patients, and the adherence rate is much higher.

UCLA neurobiologist Ronald Harper and his research group have led pioneering studies since the early 2000s showing, with magnetic resonance imaging, how obstructive sleep apnea impairs the hippocampus and associated brain structures related to short-term memory. “We would hear from these 45-year-old executives that they felt brilliant when they started their company, and now they couldn’t remember things, couldn’t think, couldn’t plan,” Harper says. “Then we would look at their scans and sure enough, we could see the damage.”

More recently, Rajesh Kumar, an associate professor of anesthesiology and radiological sciences and a former member of Harper’s lab, led a study that uncovered the first evidence that obstructive sleep apnea contributes to a breakdown of the blood-brain barrier, which protects brain tissue from harmful bacteria, infections and chemicals. “People who are having symptoms of sleep-disordered breathing need to address the problem immediately,” Harper warns. “It’s terrifying to see how much these memory bodies shrink, and once those cells go, they’re gone.”

Macey’s School of Nursing lab has provided a possible explanation for the depression-related symptoms, reporting in a series of recent studies that in regions of the brain involved in regulating emotion and blood pressure, people with obstructive sleep apnea show dramatic changes in two key brain chemicals. Macey says the discovery of what appears to be a functional reorganization of the brains of people with obstructive sleep apnea is encouraging in that “in contrast with damage, if something is working differently, potentially we can fix it.” He and his colleagues also were recently among the first to show that in children with sleep apnea — the airway obstruction typically coming from their tonsils, often exacerbated by obesity — parts of the brain associated with thinking and problem-solving were smaller.


Given the relative brevity of our time on Earth, why must we spend nearly a third of each day unconscious? One prominent theory is that we need sleep to strengthen the neural connections we make while awake — to consolidate memories. But skeptics point out that we don’t need to sleep in the afternoon to recount over dinner what happened that morning. The theory with arguably the most currency today has to do with sleep’s rejuvenative function — the refreshing of cells and filtering of waste by-products that accumulate in the brain during the day, to the potential detriment of everything from immune function to cognition.

Jerome Siegel, a professor of psychiatry at UCLA’s Semel Institute for Neuroscience and Human Behavior, challenges the notion that sleep duration is necessarily correlated with mental acuity and better health. Besides running a basic sleep research lab for more than four decades, Siegel has studied the sleeping patterns of animals in an effort to better understand human sleep. He points out that elephants, one of the longest-lived animals and with cognition believed to rival that of primates, sleep only about two hours a day. In contrast, big brown bats, hardly Einsteins, get 20 hours.

In humans, Siegel notes, large population studies consistently indicate that roughly seven hours a night is optimal for a longer lifespan, and that less-than-optimal sleep is associated with a somewhat shorter lifespan. But people at the higher ranges of average sleep time have significantly shorter life expectancies than the minimal sleepers, even when taking into account factors such as chronic illness, obesity, obstructive sleep apnea and use of sleeping pills or other sleep-inducing substances. The reasons are unclear. Nor is it clear that if you sleep eight hours or six, you’re increasing or decreasing your likelihood of a longer life because of one-hour difference from the seven-hour average.

Siegel suspects that it’s our evolutionary need for efficiency that drives sleep. “Animals have to gather their food as efficiently as possible, and those that use too much energy are not going to survive to pass on their genes,” he says. “For humans, there’s no point in expending energy throughout the night, when it’s cold and they’re going to be losing heat.” The brain is energy hungry, Siegel explains; brain metabolism declines sharply during sleep, offering a much-needed respite.

It’s also widely held that Thomas Edison is partly to blame for our current sleep shortcomings — that the advent of the electric light meant that we no longer had to go to bed so soon after sundown, cutting into our rest. To put this theory to the test, Siegel led a group that monitored the sleep habits of hunter-gatherer populations in Tanzania, Namibia and Bolivia. Despite lacking electricity, these groups stayed awake an average of 3 hours, 20 minutes past sunset, and they slept no more than the rest of us — 6 hours, 25 minutes a night.

Despite debunking that theory, Siegel does concede that technology and other temptations now dangle distractions over us in unprecedented fashion. “It’s certainly possible to sleep-deprive yourself in ways that weren’t available to our ancestors,” he says.


In some cases, our societal attitude toward sleep might need adjustment. In the UCLA Store, for example, a poster promoting a prominent energy drink proclaimed Nobody ever wishes they’d slept more in college. “We were taken aback that this advertisement, which stands in stark opposition to what we believe, was being placed in our primary student center,” recalls Robert Bilder, a neuropsychologist who heads the sleep component of the UCLA Healthy Campus Initiative, the 5-year-old effort to foster a culture of mental and physical health and wellness among UCLA students, staff and faculty. The poster was removed within 24 hours.

“SleepWell,” part of the initiative’s MindWell program, reflects campus leaders’ recognition that sleep quality and quantity are essential to physical and psychological well-being, Bilder says. To help advance that message, the program has organized special events and talks, as well as providing online resources that include tips on sleep hygiene and self-assessment tools. And in a move that would surely win Churchill’s approval, the program has posted an online “Nap Map,” which identifies nap-friendly locations on campus. “In younger people, a 15-minute nap can be the equivalent of a 20-ounce Starbucks coffee,” Avidan says. Bilder hopes the sleep-related resources and activities on campus will contribute to changing students’ mindsets.

“Too many students think it’s more important to stay up studying or socializing, and that they don’t need to sleep,” Bilder says. “It’s normal to think that one is indestructible before the age of 25, but getting a good night’s sleep is going to make you an even better superhero. Among all of the superheroes, no one ever heard of Insomnia Man.”