More sleep would make us happier, healthier and safer

Many people are surprised to learn that researchers have discovered a single treatment that improves memory, increases people’s ability to concentrate, strengthens the immune system, and decreases people’s risk of being killed in accidents. Sound too be good to be true? It gets even better. The treatment is completely free and has no side effects. Finally, most people consider the treatment highly enjoyable. Would you try it?

You probably should. For most people, this treatment would consist of getting an extra 60–90 minutes of sleep each night. Both psychologists and psychiatrists have been arguing for years that one of the most significant and overlooked public health problems in the U.S. is that many American adults are chronically sleep deprived. That is, very few Americans regularly obtain the eight or more hours of sleep that almost all adults need each night. The consequences of this chronic sleep deprivation can be disastrous. Laboratory experiments on the effects of sleep deprivation have shown that failing to get enough sleep dramatically impairs memory and concentration while increasing levels of stress hormones and disrupting the body’s normal metabolism. Research outside the laboratory further suggests that long-term sleep deprivation puts people at greater risk of motor vehicle accidents and disease.

This is important because research shows that many people are carrying a heavy “sleep debt” that they have built up from weeks, months, or even years of inadequate sleep. In experiments on sleep debt, researchers pay healthy volunteers to stay in bed for at least 14 hours a day for a week or more. Most people, given this opportunity, sleep about 12 hours a day for several days, sometimes longer—and then they settle into sleeping seven to nine hours per night. As sleep researcher William Dement, PhD, put it, “this means…that millions of us are living a less than optimal life and performing at a less than optimal level, impaired by an amount of sleep debt that we’re not even aware we carry.”

But is carrying a sleep debt really so harmful? Experiments by psychologist David Dinges, PhD, and others have shown that the answer is yes. Dinges and colleagues recruited healthy young volunteers to continuously in a sleep laboratory for 10–20 days. By randomly assigning the volunteers to receive different amounts and patterns of sleep over time, by controlling their access to stimulants such as caffeine, and by constantly monitoring their physiological states (to document the amount of sleep they were actually getting), Dinges learned that people who get fewer than eight hours of sleep per night show pronounced cognitive and physiological deficits, including memory impairments, a reduced ability to make decisions, and dramatic lapses in attention.

In fact, Dinges showed that two weeks of limited sleep—about four hours per night—created brain deficits just as severe as those seen in people who hadn’t slept at all for three nights. As sleep deprivation continues over time, attention, memory, and other cognitive functions suffer. Consistently failing to get enough sleep is the biological equivalent of consistently spending more money than you make.

Too little shuteye has been linked to increased risk of car crashes, poor work performance, and problems with mood and relationships. Sleep deprivation taxes the immune system, and is associated with a heightened risk of high blood pressure, heart disease, stroke, diabetes, obesity, and depression. People who chronically fail to get enough sleep may actually be cutting their lives short.

Napping can help reduce a sleep debt, but it’s no substitute for healthy sleep habits. There are long-term benefits to maintaining consistent, predictable sleep patterns. In addition, whereas naps do improve cognitive functioning after periods of sleep deprivation, they do not do much to repair the negative mood that results from sleep loss (see Dinges et al., 1988).

Many people argue that they get by just fine on very little sleep. However, research shows that only a tiny fraction of people can function well on fewer than eight hours of sleep each night. Dinges estimates that, over the long haul, perhaps one person in a thousand can function effectively on six or fewer hours of sleep per night. Many people who operate on chronic sleep debts end up napping during the day or fighting through long periods of sleepiness in the afternoon. Worse, most people who are sleep deprived do not even realize it. If you get sleepy during long meetings or long drives, chances are you are sleep deprived.

The Institute of Medicine estimates that 50 million to 70 million adults in the U.S. have chronic sleep disorders, and a 2009 survey by the Centers for Disease Control and Prevention found that more than 35% of people reported averaging fewer than seven hours of sleep per night.

Those sleepless nights are taking a toll. The U.S. Department of Transportation estimates that drowsy driving is responsible for 1,550 fatalities and 40,000 nonfatal injuries every year. Even small disruptions in sleep can wreak havoc on human safety and performance. For example, in a nationwide study of motor vehicle accidents occurring between 1986 and 1995, psychologist Stanley Coren, PhD, studied the effects of the single hour of lost sleep that many Americans experience when they set their clocks forward every spring. The result? A 17% increase in traffic deaths on the Mondays following the time changes (compared with the Mondays before). Other psychologists have observed similar findings. A study by Gregory J. Hicks, PhD, and colleagues, for instance, found an increase in alcohol-related traffic crashes in the week following the change to daylight saving time.

It is harder to estimate the toll sleep deprivation takes on people’s health, happiness, and productivity, but according to a 2011 report by the American Academy of Sleep Medicine, the annual cost in lost worker productivity due to sleeplessness is about $63 billion.

In light of the dramatic public health consequences of sleep deprivation and unhealthy sleep patterns, the National Sleep Foundation, in cooperation with many partner organizations, established National Sleep Awareness Week, promoted each spring during the week when people set their clocks forward for daylight saving time. During that week, sleep centers throughout North America sponsor educational activities in their local communities. Many U.S. states now educate drivers not only about the dangers of driving while intoxicated but also about the dangers of driving while drowsy.