(1) A type of sleep disorder in which sleep is deprived.
(2) A condition characterized by a lack of quality sleep, particularly during an experiment or during an atypical actual condition.
Sleep deprivation is different from insomnia or from being unable to sleep. The constant lack of sleep may lead to problems in hearing, sight, alertness, fatigue, and other brain functions. An individual may feel a rather slow reflex, daytime sleepiness, and clumsiness. Sleep deprivation may also affect individual’s weight, either resulting to loss or gain in weight.