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Sleep deprivation, a sleep disorder characterized by having too little sleep, can be either chronic or acute. Long-term sleep deprivation causes certain death in severe cases, especially with lab animals. A chronic sleep-restricted state can cause fatigue, daytime sleepiness, clumsiness and weight gains.

Complete absence of sleep over long periods is impossible to achieve; brief microsleeps cannot be avoided.^[1]

[edit] Physiological effects

Main health effects of sleep deprivation.^[2]

Generally, lack of sleep may result in^[3][4]

• aching muscles^[5]
• dizzyness and nausea
• dry mouth^{[citation needed]}
• hallucinations^[6]
• hand tremors^[7]
• headaches
• increased blood pressure^[8]
• increased risk for diabetes^[9]
• increased risk of fibromyalgia^[10]
• irritability^[3]
• memory lapses or loss^[11]
• nystagmus (rapid involuntary rhythmic eye movement)^[12]
• obesity^[9]
• slowed word recall^{[citation needed]}
• temper tantrums in children^[3]
• yawning^[3]
• symptoms similar to:
  • Attention-deficit hyperactivity disorder^[3] (ADHD)
  • psychosis^[13]

[edit] Diabetes

In 2005, a study of over 1400 participants showed that participants who habitually slept few hours were more likely to have associations with Diabetes Type 2.^[14] However, because this study was merely correlational, the direction of cause and effect between little sleep and diabetes is uncertain. The authors point to an earlier study which showed that experimental rather than habitual restriction of sleep resulted in impaired glucose tolerance (IGT).^[15]

[edit] Effects on the brain

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Sleep deprivation can adversely affect brain function.^[16] A 2000 study, by the UCSD School of Medicine and the Veterans Affairs Healthcare System in San Diego, used also functional magnetic resonance imaging technology to monitor activity in the brains of sleep-deprived subjects performing simple verbal learning tasks.^[17] The study showed that regions of the brain's prefrontal cortex displayed more activity in sleepier subjects. Depending on the task at hand, the brain would sometimes attempt to compensate for the adverse effects caused by lack of sleep.

The temporal lobe, which is a brain region involved in language processing, was activated during verbal learning in rested subjects but not in sleep deprived subjects. The parietal lobe, not activated in rested subjects during the verbal exercise, was more active when the subjects were deprived of sleep. Although memory performance was less efficient with sleep deprivation, greater activity in the parietal region was associated with better memory.

A 2001 study at Chicago Medical Institute suggested that sleep deprivation may be linked to more serious diseases, such as heart disease and mental illnesses including psychosis and bipolar disorder.^[18] The link between sleep deprivation and psychosis (psychiatric disorders) was further documented in 2007 through a study at Harvard Medical School and the University of California at Berkeley. The study revealed, using MRI scans, that lack of sleep causes the brain to become incapable of putting an emotional event into the proper perspective and incapable of making a controlled, suitable response to the event...

A 2002 University of California animal study indicated that REM sleep was necessary for turning off neurotransmitters and allowing their receptors to "rest" and regain sensitivity which allows monoamines (norepinephrine, serotonin and histamine) to be effective at naturally produced levels. This leads to improved regulation of mood and increased learning ability. The study also found that REM sleep deprivation may alleviate clinical depression because it mimics selective serotonin reuptake inhibitors (SSRI).

This is because the natural decrease in monoamines during REM is not allowed to occur, which causes the concentration of neurotransmitters in the brain, that are depleted in clinically depressed persons, to increase. Sleep outside of the REM phase may allow enzymes to repair brain cell damage caused by free radicals. High metabolic activity while awake damages the enzymes themselves preventing efficient repair. This study observed the first evidence of brain damage in rats as a direct result of sleep deprivation.^[19]

Animal studies suggest that sleep deprivation increases stress hormones, which may reduce new cell production in adult brains.^[20]

[edit] Effects on growth

A 1999 study^[21] found that sleep deprivation resulted in reduced cortisol secretion the next day, driven by increased subsequent slow-wave sleep. Sleep deprivation was found to enhance activity on the Hypothalamic-pituitary-adrenal axis (which controls reactions to stress and regulates body functions such as digestion, the immune system, mood, sex, or energy usage) while suppressing growth hormones. The results supported previous studies, which observed adrenal insufficiency in idiopathic hypersomnia.

[edit] Effects on the healing process

A study conducted in 2005 showed that a group of rats which were deprived of REM sleep for five days had no significant effect on their ability to heal wounds, compared to a group of rats not deprived of "dream" sleep.^[22] The rats were allowed deep (NREM) sleep. However, another study conducted by Gumustekin et al.^[23] in 2004 showed sleep deprivation hindering the healing of burns on rats.

[edit] Attention

Among the numerous physical consequences of sleep deprivation, attention deficits are perhaps the most important; attentional lapses in mundane routines can lead to unfortunate results, from forgetting ingredients while cooking to missing a sentence while taking notes. The attentional lapses also extend into more critical domains in which the consequences can be literally life-or-death; traffic accidents and industrial disasters can result from inattentiveness attributable to sleep deprivation.

To empirically measure the magnitude of these attention deficits, researchers typically employ the psychomotor vigilance task (PVT) which requires the subject to press a button in response to a light at pseudo-random intervals. Failure to press the button in response to the stimulus (light) is recorded as an error, attributable to the microsleeps that occur as a product of sleep deprivation.

Crucially, individuals' subjective evaluations of their fatigue often do not predict actual performance on the PVT. While totally sleep-deprived individuals are usually aware of the degree of their impairment, lapses from chronic (lesser) sleep deprivation can build up over time so that they are equal in number and severity to the lapses occurring from total (acute) sleep deprivation. Chronically sleep-deprived people, however, continue to rate themselves considerably less impaired than totally sleep-deprived participants.^[24] Since people usually evaluate their capability on tasks like driving subjectively, their evaluations may lead them to the false conclusion that they are able to perform tasks that require constant attention when their abilities are in fact impaired.

[edit] Impairment of ability

The dangers of sleep deprivation are nowhere more apparent than on the road; the American Academy of Sleep Medicine reports that one in every five serious motor vehicle injuries is related to driver fatigue, with 80,000 drivers falling asleep behind the wheel every day and 250,000 accidents every year related to sleep^[25], though the National Highway Traffic Safety Administration suggests the figure for traffic accidents may be closer to 100,000.^[26] The AASM recommends pulling off the road and taking a 15- or 20-minute nap if you begin to feel drowsy.^[25]

According to a 2000 study published in the British Medical Journal, researchers in Australia and New Zealand reported that sleep deprivation can have some of the same hazardous effects as being drunk.^[27] People who drove after being awake for 17–19 hours performed worse than those with a blood alcohol level of .05 percent, which is the legal limit for drunk driving in most western European countries. Another study suggested that performance begins to degrade after 16 hours awake, and 21 hours awake was equivalent to a blood alcohol content of .08 percent, which is the blood alcohol limit for drunk driving in Canada, the U.S., and the U.K.^[28]

In addition, as a result of continuous muscular activity without proper rest time, effects such as cramping are much more frequent in sleep-deprived individuals. Extreme cases of sleep deprivation have been reported to be associated with hernias, muscle fascia tears, and other such problems commonly associated with physical overexertion. Beyond impaired motor skills, people who get too little sleep may have higher levels of stress, anxiety and depression, and may take unnecessary risks.^{[citation needed]}

A new study has shown that while total sleep deprivation for one night caused many errors, the errors were not significant until after the second night of total sleep deprivation.^[29] However, combining alcohol with acute sleep deprivation results in a trebled rate of driving off the road when using a simulator.^[30]

The National Sleep Foundation identifies several warning signs that a driver is dangerously fatigued, including rolling down the window, turning up the radio, trouble keeping your eyes open, head-nodding, drifting out of your lane, and daydreaming. If you notice one of these cautionary signals, you should pull off the road and take a nap, even if you do not feel especially tired. At particular risk are lone drivers between midnight and 6AM, when the circadian rhythm is at its lowest point.^[31]

Sleep deprivation can negatively impact performance in professional fields as well, potentially jeopardizing lives. Due largely to the February crash of a regional jet in Buffalo, N.Y., which killed 50 people and was partially attributed to pilot fatigue, the FAA is reviewing its procedures to ensure pilots are sufficiently rested.^[32] A 2004 study also found medical residents with less than four hours of sleep a night made more than twice as many errors as residents who slept for more than seven hours a night, an especially alarming trend given that less than 11% of surveyed residents were sleeping more than seven hours a night.^[33]

[edit] Microsleeps

Microsleeps occur when a person has a significant sleep deprivation. The brain automatically shuts down, falling into a sleep state for a period that can last 10 to 60 seconds. The person mentally falls asleep no matter what activity he or she is engaged in. Microsleeps are similar to blackouts and a person experiencing them is not consciously aware that they are occurring. Great sleep deprivation mimics psychosis: distorted perceptions can lead to inappropriate emotional and behavioral responses.^[34]

[edit] Obesity

Several large studies using nationally representative samples suggest that the obesity problem in the United States might have as one of its causes a corresponding decrease in the average number of hours that people are sleeping.^[35][36][37] The findings suggest that this might be happening because sleep deprivation could be disrupting hormones that regulate glucose metabolism and appetite.^[38]

The association between sleep deprivation and obesity appears to be strongest in young and middle-age adults. Other scientists hold that the physical discomfort of obesity and related problems, such as sleep apnea, reduce an individual's chances of getting a good night's sleep.

[edit] Uses

[edit] Scientific study

In science, sleep deprivation (of rodents, e.g.) is used in order to study the function(s) of sleep and the biological mechanisms underlying the effects of sleep deprivation. Sleep deprivation can result in a form of psychosis if sleep is deprivated for more than 5 days.^{[citation needed]}

Some sleep deprivation techniques are as follows:

• Gentle handling (often require polysomnography): during the sleep deprivation period, the animal and its polygraph record are continuously observed; when the animal displays sleep electrophysiological signals or assumes a sleep posture, it is given objects to play with and activated by acoustic and if necessary tactile stimuli.^[39] Although subjective,^[40] this technique is used for total sleep deprivation as well as REM or NREM sleep deprivation.

This rat is being deprived of restful REM sleep by an animal researcher using a single platform ("flower pot") technique. The water is within 1 cm of the small flower pot bottom platform where the rat sits. At the onset of REM sleep, the exhausted rat would either fall into the deep water only to clamber back to its pot to avoid death from drowning, or its nose would become submerged into the water shocking it back to an awakened state.

• Single platform: probably one of the first scientific methods (see Jouvet, 1964^[41] for cats^[42] and for rodents). During the sleep deprivation period, the animal is placed on an inverted flower pot whose bottom diameter is small relative to the animal size (usually 7 cm for adult rats); the pot is placed in a large tub filled with water to within 1 cm of the flower pot bottom. The animal is able to rest on the pot and is even able to get NREM sleep. But at the onset of REM sleep, with its ensuing muscular relaxation, it would either fall into the water and clamber back to its pot or would get its nose wet enough to waken it. So this technique is used only for REM sleep deprivation.
• Multiple platform: in order to reduce the elevated stress response induced by the single platform method,^[43] developed this technique in which the animal is placed into a large tank containing multiple platforms, thus eliminating the movement restriction experienced in the single platform. This technique is also used only for REM sleep deprivation.
• Modified multiple platform: modification of the multiple platform method where several animals together get the sleep deprivation (Nunes and Tufik, 1994).
• Pendulum: animals are prevented from entering into PS by allowing them to sleep for only brief periods of time. This is accomplished by an apparatus which moves the animals' cages backwards and forwards like a pendulum. At the extremes of the motion postural imbalance is produced in the animals forcing them to walk downwards to the other side of their cages.^[44]

[edit] Torture

Sleep deprivation can be used as a means of interrogation that some believe will constitute torture when used to excess. Under one interrogation technique, a subject might be kept awake for several days and when finally allowed to fall asleep, suddenly awakened and questioned. Menachem Begin, the Prime Minister of Israel from 1977-83, described his experience of sleep deprivation when a prisoner of the NKVD in Russia as follows:

In the head of the interrogated prisoner, a haze begins to form. His spirit is wearied to death, his legs are unsteady, and he has one sole desire: to sleep...Anyone who has experienced this desire knows that not even hunger and thirst are comparable with it.^[45]

Sleep deprivation is one of the five techniques used by the British government in the 1970s. The European Court of Human Rights ruled that the five techniques "did not occasion suffering of the particular intensity and cruelty implied by the word torture ... [but] amounted to a practice of inhuman and degrading treatment", in breach of the European Convention on Human Rights.^[46]

In 2006, Australian Federal Attorney-General Philip Ruddock argued that sleep deprivation does not constitute torture.^[47] In rats, prolonged, complete sleep deprivation increases both food intake and energy expenditure, leading to weight loss and, ultimately, death.^[48] Nicole Bieske, a spokeswoman for Amnesty International Australia, has stated, "At the very least, sleep deprivation is cruel, inhumane and degrading. If used for prolonged periods of time it is torture."^[49]

[edit] Treatment for depression

Recent studies show sleep deprivation has some potential in the treatment of depression. About 60% of patients, when sleep-deprived, show immediate recovery, with most relapsing the following night. The effect has been shown to link to increases in brain-derived neurotrophic factor (BDNF).^[50] It has been shown that chronotype is related to the effect of sleep deprivation on mood in normal people; those with morningness circadian preference show an increase in depression-dejection scores while those with eveningness preference show a significant decrease.^[51]

The incidence of relapse can be decreased by combining sleep deprivation with medication.^[52] Many tricyclic antidepressants happen to suppress REM sleep, providing additional evidence for a link between mood and sleep.^[53] Similarly, tranylcypromine has been shown to completely suppress REM sleep at adequate doses.

[edit] Voluntary

Sleep deprivation has sometimes been self-imposed to achieve personal notoriety in the context of record-breaking stunts. One such record belonged to Randy Gardner, who stayed awake for 264 hours (eleven days). Lt. Cmdr. John J. Ross of the US Navy Medical Neuropsychiatric Research Unit later published an account of this event, which became well known among sleep-deprivation researchers. In 2004, Shattered was a controversial British reality television competition where contestants competed to go for 7 full days sleeping just one hour per day.

[edit] Causes and treatments

[edit] Mental Health

A potential cause of sleep deprivation is a chemical imbalance in brain activity,^{[citation needed]} such as those associated with mania or hypomania. Manic individuals are often capable of long periods without sleep, or with very little sleep.

[edit] School

A National Sleep Foundation survey found that college/university-aged students get an average of 6.8 hours of sleep each night.^[54] Sleep deprivation is common in college freshmen as they adjust to the stress and social activities of college life. A study performed by the Department of Psychology at the National Chung Cheng University in Taiwan concluded that freshmen received the shortest amount of sleep during the week.^[55]

Students get more sleep each night in the summer than during the school year,^{[citation needed]} and one in four U.S. high school students admit to falling asleep in class at least once a week.^[56] Research has indicated that teenage children have a variation in their circadian cycle that delays sleep past the normal time for adults. Since school schedules are based around the adult workday, it is not surprising that students have difficulty obtaining adequate sleep.^{[citation needed]} It is known that during human adolescence, sleep patterns typically undergo marked changes. Electroencephalogram (EEG) studies indicate a 50% reduction of deep (stage 4) sleep and a 75% reduction in the peak amplitude of delta waves during nonrapid-eye movement sleep in adolescence.School schedules are often incompatible with a corresponding delay in sleep offset, leading to a less than optimal amount of sleep for the majority of adolescents.^[57]

In 1997 the University of Minnesota did research that compared students who went to school at 7:15 a.m. and those who went to school at 8:40 a.m. They found that students who went to school at 8:40 got higher grades and more sleep on weekday nights.^[26]

[edit] Counteracting Sleep Deprivation

Several strategies are common in attempting to increase alertness and counteract the effects of sleep deprivation. Caffeine, the most commonly used stimulant in the U.S., is often used over short periods to boost wakefulness when experiencing acute sleep deprivation; however, large doses are required, and caffeine is less effective if taken routinely. Other strategies recommended by the American Academy of Sleep Medicine include polyphasic sleep before deprivation, naps, other stimulants, and combinations therein. However, the only sure and safe way to combat sleep deprivation is to increase nightly sleep time.^[58]

[edit] Longest period without sleep

Depending on how sleep is defined, there are several people who can claim the record for having gone the longest without sleep:

1. Thai Ngoc, born 1942, claimed in 2006 to have been awake for 33 years or 11,700 nights, according to Vietnamese news organization Thanh Nien. It was said that Ngoc acquired the ability to go without sleep after a bout of fever in 1973,^[59] but other reports indicate he stopped sleeping in 1976 with no known trigger.^[60] At the time of the Thanh Nien report, Ngoc suffered from no apparent ill effect (other than a minor decline in liver function), was mentally sound and could carry 100 kg of pig feed down a 4 km road,^[59] but another report indicates that he was healthy before the sleepless episode but that now he was not feeling well because of the lack of sleep.^[60]
2. In January 2005, the RIA Novosti published an article about Fyodor Nesterchuk from the Ukrainian town of Kamen-Kashirsky who claimed to have not slept in more than 20 years. Local doctor Fyodor Koshel, chief of the Lutsk city health department, claimed to have examined him extensively and failed to make him sleep. Koshel also said however that Nesterchuck did not suffer any of the normally deleterious effects of sleep deprivation.^[61] People who claim not to sleep are usually shown to sleep when studied in sleep laboratories with EEG. Nesterchuck reports experiencing drowsiness at night, commenting that he attempts to sleep "in vain" when he notices his eyelids drooping. Many people experience microsleep episodes during sleep deprivation, in which they sleep for periods of seconds to fractions of a second and frequently don't remember these episodes. Because microsleep is frequently not remembered, microsleep or a related phenomenon may be responsible for lack of sleep and/or lack of memory of sleep in individuals like Nesterchuk and Thai Ngoc.
3. Randy Gardner holds the scientifically documented record for the longest period of time a human being has intentionally gone without sleep not using stimulants of any kind. Gardner stayed awake for 264 hours (eleven days), breaking the previous record of 260 hours held by Tom Rounds of Honolulu.^[62] Other sources claim that the Guinness World Records record stands at 449 hours (18 days, 17 hours), held by Maureen Weston, of Peterborough, Cambridgeshire in April, 1977, in a rocking-chair marathon.^[63]
4. The toddler Rhett Lamb^[64] of St. Petersburg, Florida, has a rare condition and slept only one to two hours per day in the first three years of his life. He has a rare abnormality called an Arnold-Chiari malformation where brain tissue protrudes into the spinal canal; the skull puts pressure on the protruding part of the brain. The boy was operated on at All Children's Hospital in St. Petersburg in May 2008. Two days after surgery he slept through the night.^[65][66]

[edit] See also

• Fatal Familial Insomnia
• Fatigue
• Insomnia
• Narcolepsy
• Polyphasic sleep
• Sleep debt
• Sleep medicine
• Sleep onset latency
• Touch the Truck
• Wake therapy

[edit] References

[edit] External links

• Brain activity is visibly altered following sleep deprivation
• "How Much Sleep Do You Really Need?", U.S. National Sleep Foundation
• National Sleep Foundation 2005 Sleep in America Poll
• Why Do Humans and Many Other Animals Sleep?