Consequences of sleep deprivation

I'm a mess if I don't get enough sleep!  You probably recognize the ill effects of sleep deprivation after a night or two of not sleeping well: grogginess, grouchiness and a brain that doesn't function like it should.  But what many people don't know is that there's a wide range of health problems that can occur if you are completely or partially sleep deprived. Here's what a Harvard report, Improving Sleep: A Guide to a Good Night's Rest has to say on the subject: 

Normally, you go about 16 or 17 hours between sleep sessions. Complete sleep deprivation happens as the hours extend beyond this point. First you feel tired, then exhausted. By 2 or 3 a.m., many people have a hard time keeping their eyes open, but the effects extend throughout the body. Simple tasks that you would normally have no trouble accomplishing start to become difficult.

In fact, a number of studies of hand-eye coordination and reaction time have shown that such sleep deprivation can be as debilitating as being intoxicated. In one study, volunteers stayed awake for 28 hours, beginning at 8 a.m., and periodically took driving simulation tests. At a different time, the volunteers' driving ability was tested after drinking 10 to 15 grams of alcohol at 30-minute intervals until their blood alcohol content (BAC) level reached 0.10. The study concluded that 24 hours of wakefulness had the same deleterious effect on driving ability as that of a BAC of 0.10 — enough to be charged with driving while intoxicated in most states.

Sleep deprivation also leaves you prone to two potentially dangerous phenomena, microsleeps and automatic behavior (see below), which play a role in thousands of transportation accidents each year. When complete sleep deprivation extends for two or three days, people have difficulty completing tasks demanding a high attention level and often experience mood swings, depression, and increased feelings of tension.

Partial sleep deprivation occurs when you get some sleep, but not 100% of what you need. Experts refer to this as building up a sleep debt. An example would be when a person who needs 7.5 hours of sleep a night hits a stretch of several days in a row in which he or she only gets four to six hours.

After a single night of short sleep, most people function at or near their normal level. They may not feel great, but they can usually get through the day without others noticing that anything is amiss. After two or more nights of short sleep, people usually show signs of irritability and sleepiness. Work performance begins to suffer — particularly on complicated tasks — and people are more likely to complain of headaches, stomach problems, and sore joints. In addition, people face a far higher risk of falling asleep on the job and while driving.

Long-term partial sleep deprivation occurs when someone gets less than the optimal amount of sleep for months or years on end — a common scenario for insomniacs and people with sleep disorders. But even healthy people who can't resist the round-the-clock commerce, communication, and entertainment opportunities our 24/7 society now offers may fall prey to this problem.

A growing number of studies have linked long-term sleep deficits with significant health problems.

Obesity. A 2006 study found that over 16 years, middle-aged women who reported sleeping five hours or less per night were 32% more likely to gain 33 pounds or more than women who slept seven hours or more. Another study found that men limited to four hours of sleep for two consecutive nights experienced hormonal changes that made them feel hungry and crave carbohydrate-rich foods such as cakes, candy, ice cream, and pasta.

Heart health. Middle-aged people who sleep five hours or less a night have a greater risk of developing high blood pressure, compared with people who sleep seven to nine hours a night. Women who averaged five hours of sleep a night were 39% more likely to develop heart disease than women who slept eight hours.

Mental health. A number of studies have found that persistent insomnia raises the risk for anxiety, depression, and other mood disorders.

Mortality. A study of almost a million people over age 30 found that men who reported usually sleeping less than four hours a day were nearly three times as likely to die within six years as men who said they averaged seven or eight hours of sleep.

Have you ever been completely or partially sleep deprived? What was your experience like?

Julie K. Silver, M.D., is an assistant professor in the Department of Physical Medicine and Rehabilitation at Harvard Medical School. She is also the Chief Editor of Books for Harvard Health Publications.

Good Night's Sleep

Sleep can be as important to your health as diet and exercise, but for many people, falling and staying asleep isn't easy. The Harvard Medical School Guide to a Good Night's Sleep lays out a six-step plan to improve sleep and deal with common issues like insomnia, disrupted sleep, sleepwalking, and the many other chronic sleep conditions that affect more than 70 million Americans. Through lifestyle and environment changes, you can finally sleep soundly—without necessarily having to take a pill.

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