Sleep deprivation is the condition of not having enough sleep; it can be either chronic or acute. A chronic sleep-restricted state can cause fatigue, daytime sleepiness, clumsiness and weight loss or weight gain. It adversely affects the brain and cognitive function. Few studies have compared the effects of acute total sleep deprivation and chronic partial sleep restriction. Complete absence of sleep over long periods is impossible for humans to achieve (unless they suffer from fatal familial insomnia); brief microsleeps cannot be avoided. Long-term total sleep deprivation has caused death in lab animals.
Generally, sleep deprivation may result in:
•confusion, memory lapses or loss
•sensitivity to cold
•periorbital puffiness, commonly known as "bags under eyes" or eye bags •increased blood pressure
•increased stress hormone levels
•increased risk of diabetes
•increased risk of fibromyalgia
•nystagmus (rapid involuntary rhythmic eye movement)
•temper tantrums in children
•symptoms similar to:
oAttention-deficit hyperactivity disorder (ADHD)
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.  Effects on the brain
Sleep deprivation can adversely affect the brain and cognitive function. 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, an area that supports mental faculties such as working memory and logical and practical ("means-ends")...