Sleep deprivation
Sleep deprivation is a general lack of the necessary amount of sleep. This may occur as a result of sleep disorders, active choice or deliberate inducement such as in interrogation or for torture. Studies have reported that sleep deprivation affects tens of millions of adults each year in the United States alone..

# Effects
Generally, lack of sleep may result in:
- aching muscles;
- blurred vision;
- Cardiovascular disease;
- clinical depression;
- colorblindness;
- daytime drowsiness and naps;
- decreased mental activity and concentration;
- depersonalization/derealization;
- weakened immune system;
- dizziness;
- dark circles under the eyes;
- fainting;
- general confusion;
- hallucinations;
- hand tremors;
- headache;
- hernia;
- hyperactivity;
- hypertension;
- impatience;
- irritability;
- Lucid dreaming (once sleep resumes);
- memory lapses or loss;
- nausea;
- nystagmus (rapid involuntary rhythmic eye movement);
- psychosis;
- pallor;
- slowed reaction time;
- slurred and/or nonsensical speech;
- weight loss or gain;
- yawning;
- symptoms similar to:
Attention deficit Hyperactivity Disorder;
Alcoholic Intoxication.
- Attention deficit Hyperactivity Disorder;
- Alcoholic Intoxication.

## Diabetes
A 1999 study by the University of Chicago Medical Center showed that sleep deprivation severely affects the human body's ability to metabolize glucose, which can lead to early-stage Diabetes Type 2.

## Effects on the brain
Sleep deprivation can adversely affect brain function. A 2000 study, by the UCSD School of Medicine and the Veterans Affairs Healthcare System in San Diego, used functional magnetic resonance imaging technology to monitor activity in the brains of sleep-deprived subjects performing simple verbal learning tasks. 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 Harvard's Medical Institute suggested that sleep deprivation may be linked to more serious diseases, such as heart disease.
Animal studies suggest that sleep deprivation increases stress hormones, which may reduce new cell production in adult brains.

## Effects on growth
A 1999 study 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.

## Effects on the healing process
A study conducted in 2005 showed that a group of rats who were deprived of five days of sleep had no significant effect on their ability to heal wounds, compared to a group of rats not deprived of sleep.

## Impairment of ability
According to a 2000 study published in the British scientific journal, researchers in Australia and New Zealand reported that sleep deprivation can have some of the same hazardous effects as being drunk. People who drove after being awake for 1719 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 (the U.S. and UK set their blood alcohol limits at .08 percent). 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. According to the National Highway Traffic Safety Administration, over 100,000 traffic accidents each year are caused by fatigue and drowsiness. 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.
The response latency seem to be higher when it comes to actions regarding personal morality rather than in situations when morality is not in question. The willingness to violate a personal belief has been shown to be moderated by EQ, so people with high EQ are affected less by sleep deprivation in such situations.

## Obesity
Several large studies using nationally representative samples suggest that the obesity epidemic in Europe and the United States might have as one of its causes a corresponding decrease in the average number of hours that people are sleeping.  The findings suggests that this might be happening because sleep deprivation might be disrupting hormones that regulate glucose metabolism and appetite. 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.

# Uses

## 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.
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. Although subjective, this technique is used for total sleep deprivation as well as REM or NREM sleep deprivation.
- single platform: probably one of the first scientific methods (see Jouvet, 1964 for cats and for rodents). During the sleep deprivation period, the animal is placed on an inverted flower pot whose bottom diameter is 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, 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.

## Torture
Sleep deprivation is used as a torture or interrogation technique (for example, in Pinochet-era Chile, the Soviet Union, and by coalition forces in Afghanistan). Interrogation victims are kept awake for several days; when they are finally allowed to fall asleep, they are suddenly awakened and questioned. Menachem Begin, the Israeli prime minister from 1977-83 described his experience of sleep deprivation when a prisoner of the KGB 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." In 2006, Australian Federal Attorney-General Philip Ruddock argued that sleep deprivation does not constitute torture.  In rats, prolonged, complete sleep deprivation increases both food intake and energy expenditure, leading to weight loss and, ultimately, death.  Nicole Bieske, a spokeswoman for Amnesty International Australia, has stated, "At the very least,  is cruel, inhumane and degrading. If used for prolonged periods of time it is torture."

## 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 incidence of relapse can be decreased by combining sleep deprivation with medication . Incidentally, many tricyclic antidepressants happen to suppress REM sleep, providing additional evidence for a link between mood and sleep . Similarly, tranylcypromine has been shown to completely suppress REM sleep at adequate doses.

## Voluntary
Sleep deprivation is often used as a form of recreation, entertainment or to provide a legal "high" without using drugs. Vivid hallucinations, heightened senses and a feeling of incredible creativity (common effects of illicit drugs) may occur after 48 hours (or less) of being in a state of sleeplessness.
There is even a history of sleep deprivation being used by different schools of religious mystics as a form of asceticism or to heighten spiritual awareness. In particular the early desert monks of the Christian Church during the fourth and fifth centuries were known to deny themselves sleep. Coffee owes much of its spread through use by Muslim mystics in all-night devotions.

# Causes and treatments

## School
In the United States, and in many other countries, sleep deprivation is common among students due to the fact that almost all schools begin early in the morning, forcing students to get less sleep than they normally would. In addition, students who should be getting between 8.5 and 9.25 hours of sleep, are getting only 7 hours due to school policies. In most studies, the issues of parental responsibility over their children's lifestyle was not introduced.  In several school districts, the opening of school was delayed by over an hour to give students more sleep. For example, in 1997 the University of Minnesota did research that compared students who went to school at 7:15 and those who went to school at 8:40. They found that students who went to school at 8:40 got higher grades and more sleep on the weekdays. A National Sleep Foundation  survey found that students get an average of 6.8 hours of sleep. Students get more sleep each night in the summer than during the school year. One in four US high school students admits to falling asleep in class at least once a week.

## Prevention of effects in soldiers
Since sleep deprivation is a fact of modern combat, the U.S. Army, through DARPA, has a "Preventing Sleep Deprivation Program", which has the goal to prevent the harmful effects of sleep deprivation and provide methods for recovery of function with particular emphasis on  cognitive and psychomotor impairments. Their efforts include new pharmaceuticals that enhance neural transmission, nutraceuticals that promote neurogenesis, cognitive training, and devices such as transcranial magnetic stimulation.
Militaries of several countries, including the US, the UK, and France, have been exploring the use of a drug called modafinil (brand name Provigil), which has prevented negative effects of sleep deprivation. Although modafinil is not a typical stimulant, it eliminates fatigue, promotes wakefulness, and improves alertness; it was initially developed for sufferers of narcolepsy.