Sleep deprivation is a general lack of the necessary amount of sleep. A person can be deprived of sleep by their own body and mind, as a consequence of some sleep disorders, or deliberately. Sleep deprivation has sometimes been used as an interrogation technique or as an instrument of torture. It has been reported that sleep deprivation affects tens of millions of adults each year.. Sleep deprivation (in sleep deprivation therapy) has also been used as a treatment for depression.