Sleep deprivation

Sleep deprivation is an overall lack of the necessary amount of sleep. A person can be deprived of sleep by their own body and mind, insomnia, or actively deprived by another individual. Sleep deprivation is sometimes used as an instrument of torture, but it has also been shown to be an effective treatment of depression and other mental illnesses as well. Sleep deprivation afflicts 47 million adults in the United States.

Lack of sleep may also result in irritability, blurred vision, slurred speech, memory lapses, overall confusion, hallucinations, nausea, psychosis, and eventually death.

As a cause of death
Total sleep deprivation in rats leads to death in around 28 days. Death occurs later if only REM or only NREM sleep are eliminated. In humans, extended sleep deprivation causes microsleep sessions to develop. A person who has fatal familial insomnia may die after several months with no sleep at all; people without this condition may experience dementia or develop permanent personality changes within the first few weeks. In some rare cases, however, people have gone for months - or even years - without sleep, with limited or no adverse side effects. 

As a cause of diabetes
A 1999 study by the University of Chicago Medical Center shows that sleep deprivation severely affects the human body's ability to metabolize glucose, which can lead to early-stage diabetes.

Effects on the brain
A 2000 study by the UCSD School of Medicine and the Veterans Affairs Healthcare System in San Diego, used functional magnetic resonance imaging (fMRI) 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 (PFC) displayed more activity in sleepier subjects. Depending on the task at hand, in some cases the brain attempts 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 lobes, 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.

The British television reality show Shattered aired in 2004, in which contestants had to endure seven days with very little sleep. The effects of sleep deprivation on the brain were captured on 24/7 cameras. The show is considered the most well known sleep deprivation experiment to date.

Effects on growth
According to a study by Alexandros N. Vgontzas, George Mastorakos, Edward O. Bixler, Anthony Kales, Philip W. Gold & George P. Chrousos, published in Clinical Endocrinology, Volume 51 Issue 2 Page 205, August 1999:

"Sleep deprivation results in a significant reduction of cortisol secretion the next day and this reduction appears to be, to a large extent, driven by the increase of slow wave sleep during the recovery night. Deep sleep has an inhibitory effect on the HPA axis while it enhances the activity of the GH axis. In contrast, sleep disturbance has a stimulatory effect on the HPA axis and a suppressive effect on the GH axis. These results are consistent with the observed hypocortisolism in idiopathic hypersomnia and HPA axis relative activation in chronic insomnia. Finally, our findings support previous hypotheses about the restitution and immunoenhancement role of slow wave (deep) sleep."

Impairment of ability
According to a 2000 study published in the British scientific journal Occupational and Environmental Medicine, researchers in Australia and New Zealand reported that sleep deprivation can have some of the same hazardous effects as being drunk. Getting less than 6 hours a night can affect coordination, judgment and reaction time. 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 (most U.S. states set their blood alcohol limits at .08 percent). The study stated that 16 to 60 percent of road accidents involve sleep deprivation. Beyond impaired motor skills, people who get too little sleep may have higher levels of stress, anxiety and depression, and may take unnecessary risks.

As a cause of obesity
A 2005 large study of a nationally representative sample of about 10,000 adults, suggested that the U.S.' obesity epidemic might have as one of its causes a corresponding decrease in the average number of hours that Americans are sleeping. Some scientists speculate that this might be happening because sleep deprivation might be disrupting hormones that regulate appetite. The study found that people between the ages of 32 and 49 who sleep less than 7 hours a night are significantly more likely to be obese. 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.

As a treatment for depression
Recent studies show sleep deprivation has some potential in the treatment of depression. 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.

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.

The United States Military has recently begun to explore the use of a new drug called modafinil, which has prevented the negative effects of sleep deprivation in soldiers. Modafinil may increase wakefulness through activation of noradrenergic and dopaminergic systems, possibly through interaction with the hypocretin/orexin system PMID 15532213.