Sleep Deprivation (Cont'd)

Subjects may start to experience illusions (distorted perceptions of objects) as well as hallucinations (perceptions of nonexistent objects). They may also experience auditory hallucinations, such as hearing voices in the sound of running water. But it is on the fourth day that things really start falling apart. Subjects typically become paranoid, sometimes believing the experimenters are plotting against them. It is possible to keep sleep-deprived subjects awake for longer than 4 days, but clearly prolonged sleep deprivation is of questionable ethical justification. Surprisingly, however, there is no documentation of anyone dying or becoming seriously and chronically ill solely from lack of sleep.