Effects of Sleep DeprivationMarch 15th, 2012 | Posted by in Sleep Deprivation
The long-term deprivation of sleep can be harmful to human beings. There is a disorder called fatal familial insomnia. In this disorder, individuals experience increasingly severe disturbances in sleep. Slow-wave sleep finally disappears and only brief periods of REM (random eye movement phase when people have dreams) sleep occurs. This disease is fatal, but whether this is due to the sleep disturbances themselves, or whether the sleep disturbances are simply a sign of other neurological problems, remains uncertain.
Studies with animals also suggest that long-term deprivation of sleep can be harmful. Researchers place one experimental rat on a platform surrounded by water. Whenever the animal begins to fall asleep, the platform is rotated so that the animal must wake up and move to avoid falling into the water. The other rat (control animal) is also forced to move, but because this rat may or may not be asleep at the time, its sleep is not necessarily disturbed. The procedure reduced sleep time by 87 percent for the experimental animal and 31 percent for the control animal. Findings indicated that sleep deprivation adversely affected health. The control animal remained in perfect health whereas experimental animal became weak and uncoordinated; it lost its ability to regulate its body temperature. Similar experiments cannot be conducted with human beings. Hence it is difficult make direct inferences.
Recuperation theories of sleep make specific predictions about the effects of sleep deprivation. Because recuperation theories are based on the proposition that sleep is a response to the accumulation of debilitating effect of wakefulness it is predicted that long periods of wakefulness would produce physiological and behavioral disturbances. These disturbances would grow steadily worse as the sleep deprivation continues. After a period of deprivation has ended much of the missed sleep would be regained.
Two classic sleep deprivation case studies indicate some of the instances of effects. A researcher reports the case study of a group of sleep deprived students. While there are many differences in subjective experiences of the sleep–evading persons, there were common features. During the first night the subject did not feel very tired or sleepy. He could read or study or do laboratory work, without much attention from watcher. But he usually felt an attack of drowsiness between 3 am and 6 am. Next morning the subject felt well, except for a slight uneasiness which always appeared on sitting down and resting for any length of time. However, if he occupied himself with ordinary daily task he was likely to forget having spent a sleepless night. During the second night, reading or study was almost impossible. Again between 3 am and 6 am, desire for sleep was overpowering. Later in the morning the sleepiness diminished once more and the subject could perform some routine work. It was not safe for him to sit down however, without danger of falling asleep.
As a part of a 1965 science fair project in the US, Randy Gardner and two classmates planned to break the then world record of 260 hours of wakefulness. Randy succeeded to stay awake for 11 days on no case his behavior was abnormal or disordered. He went to sleep after 264 hours and 12 minutes. When asked how he managed to stay awake for 11 days, he replied politely “It’s just mind over matter”. He slept 14 hours the first night and gradually got back to 8 hour schedule.
Mrs. Maureen Weston later supplanted Randy Gardner in the Guinness Book of Records. During a rocking chair marathon in 1977, she kept rocking for 449 hours (18 days, 17 hours) – an impressive record of rocking round the clock.
Investigations have assessed the effects on human subjects of sleep-deprivation schedules ranging from a slightly reduced amount of sleep during one night to total sleep deprivation for several nights. The effects have been noted with respect to mood, cognition, motor performance and physiological functions.
Even moderate amounts of sleep deprivation – for example, 3 or 4 hours in one night-have been found to have three consistent effects. First, sleep-deprived subjects display an immense sleepiness. They report being more sleepy, and they fall asleep more quickly if given the opportunity. Second, sleep-deprived subjects display disturbances on various written tests of mood. Third, they perform poorly on tests of vigilance, such as looking at a series of colored lights and responding when encountering green light.
After 2 or 3 days of continuous sleep deprivation, people experience micro-sleeps. Micro-sleeps are brief periods of sleep, typically about 2 or 3 seconds long, during which eyelids droop and the subjects become less responsive to external stimuli, even though they remain standing or sitting. Micro-sleeps disrupt performance.
Remarkably the effects of sleep deprivation on cognitive functions, motor performance and physiological functions have been less consistent. Deficits have been observed in some studies but not in others even after lengths periods of deprivation. For example, some researchers found that periods of sleep deprivation lasting up to 72 hours had no effect on physical strength or motor performance, except for reducing time to exhaustion. Complex cognitive ability, such as IQ tests, have proven to be largely immune to disruption by sleep deprivation. Although performance on intelligence test is influenced little by sleep deprivation, performance on tests of creativity is disrupted.
If subjects were deprived of the opportunity to eat, the effects would be severe and unavoidable. Starvation and death would ensue. These have been no such dramatic effects reported in sleep deprivation studies.
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