In humans studies have shown that we need to dream. REM deprivation studies have shown that dreams come out in the waking state making the subjects act and seem a bit looney so to speak. We still do not know whether there is a need to dream or not, but is evident that the body requires REM sleep. REM deprivation does not lead to psychosis, bizarre behaviour, anxiety or irritability, as was once feared (Kelly, Kandel). Subjects deprived of REM sleep for as long as 16 days shows no signs of serious psychological disturbance.

The most important effect of REM deprivation is a dramatic shift in subsequent patterns when the subject is allowed to sleep without interruption. Curtailment of REM sleep for several nights is followed by earlier initiation, marked lengthening, and increased frequency of REM periods (Kelly, Kandel). The longer the deprivation the larger and longer the REM rebound. The existence of an active compensatory mechanism for the recovery of lost or suppressed REM sleep suggests that REM sleep is physiologically necessary.

Webb (1985), found that sleep loss over 48 hours had little effect on precision and cognitive processing tasks, whereas subjective and attention measures suffered. Performance may be more due to motivational factors than cognitive components.

Lugaresi et al (1986) reported the case of a man who gradually began to sleep less and less; he suffered from waking dreams, disorientation, inability to concentrate and lack of intelligibility. When he died, he was found to have an inherited condition that caused his thalamus to degenerate.