Sleep loss

Sleep deprivation, also known as insufficient sleep or sleeplessness, is the condition of not having enough sleep. It can be either chronic or acute and may vary widely in severity. A chronic sleep-restricted state can cause fatigue, daytime sleepiness, clumsiness and increased appetite leading to weight gain. It adversely affects the brain and cognitive function. However, in a subset of cases sleep deprivation can, paradoxically, lead to increased energy and alertness and enhanced mood; although its long-term consequences have never been evaluated, it has even been used as a treatment for depression. Few studies have compared the effects of acute total sleep deprivation and chronic partial sleep restriction. Complete absence of sleep over long periods is not frequent in humans (unless they suffer from fatal familial insomnia or specific issues caused by surgery); it appears that brief microsleeps cannot be avoided. Long-term total sleep deprivation has caused death in lab animals. Generally, sleep deprivation may result in: It has been suggested that people experiencing short-term sleep restrictions process glucose more slowly than individuals receiving a full 8 hours of sleep, increasing the likelihood of developing type 2 diabetes. In 2005, a study of over 1400 participants showed that participants who habitually slept few hours were more likely to have associations with type 2 diabetes. 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). Sleep deprivation can adversely affect the brain and cognitive function. A 2000 study, by the University of California, San Diego 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, an area that supports mental faculties such as working memory and logical and practical ('means-ends') reasoning, displayed more activity in sleepier subjects. Researchers interpreted this result as indicating that the brain of the average sleep-deprived subject had to work harder than that of the average non-sleep-deprived subject to accomplish a given task. They therefore concluded that the brains of sleep-deprived subjects were attempting to compensate for adverse effects caused by sleep deprivation. The temporal lobe, 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. Getting less than the required number of hours needed to function leads to a decline in memory and judgement, this change in brain chemicals often leads to depression. Although memory performance was less efficient with sleep deprivation, greater activity in the parietal region was associated with better short term memory. A link between sleep deprivation and psychosis was documented in 2007 through a study at Harvard Medical School and the University of California at Berkeley. The study revealed, using MRI scans, that sleep deprivation 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.