Consequences of sleep deprivation
Date Posted: October 1, 2007
In-Depth Report
Consequences of sleep deprivation
Many people don't realize that lack of sufficient sleep can lead to a range of ill effects, triggering mild to potentially life-threatening consequences. There are several different types of sleep deprivation that vary in duration and severity. These can be broadly categorized as complete or partial sleep deprivation.
Complete sleep deprivation
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.
Performance is also highly influenced by fluctuations in circadian rhythms. For example, sleep-deprived people may still function fairly well during the morning and evening. But during the peaks of sleepiness in the afternoon and overnight hours, people often literally cannot stay awake and may fall asleep while standing, sitting, or even while talking on the telephone, working on the computer, or eating. A small percentage experience paranoia and hallucinations.
Microsleeps and automatic behaviorMicrosleeps are brief episodes of sleep that occur in the midst of ongoing wakeful activity. They usually last a few seconds but can go on for 10 or 15 seconds. Brain wave monitoring by EEG of someone experiencing microsleeps shows brief periods of Stage N1 sleep intruding into wakefulness. During this time, the brain does not respond to noise or other sensory inputs and you don't react to things happening around you. "Nodding off" can be the result of a microsleep. Automatic behavior refers to a period of several minutes or more during which a person is awake and performing routine duties but not attending to his or her surroundings or responding to changes in the environment. Examples include a driver who keeps his car on the road but misses his intended exit and a train engineer who can continue pressing a lever at regular intervals but doesn't notice an obstruction on the track. |
Partial sleep deprivation
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.
Sleep as part of a healthy lifestyle
Clearly, getting enough sleep is just as important as other vital elements of good health, such as eating a healthy diet, getting regular exercise, and practicing good dental hygiene. In short, sleep is not a luxury but a basic component of a healthy lifestyle.
Just like purchasing healthy foods, taking an after-dinner walk, or flossing your teeth, getting adequate sleep requires time and discipline. Mentally block off certain hours for sleep and then follow through on your intention, avoid building up a sleep debt, and take steps to set up an ideal sleep environment. Seek a doctor's help if conventional steps toward good sleep don't work.
This doesn't mean that you can't have any fun, or that you need to beat yourself up if you don't get eight hours of sleep 365 days a year. Just as an occasional ice cream sundae won't make you obese, staying up a few extra hours for a party or to meet a deadline is perfectly acceptable — as long as you make plans to compensate the next day by sleeping in, taking a short afternoon nap, or going to bed earlier. If you have to get up at 7 a.m. to be at work by 9, you'd best forgo late-night talk shows — or record them to watch the next evening. If you don't get to bed until 2 a.m. one night, allow time over the next day or two to catch up on lost sleep. But over the long haul, you need to make sure you consistently get enough sleep.
Sleep decisions are a quality-of-life issue. Whatever your interests and goals, getting enough sleep puts you in a better position to enjoy and achieve them.
Review Date: 2007-10-01
Harvard Medical School does not endorse products or services.
Share
preview