Intensive care unit psychosis

Sensory deprivation (being put in a room often without windows, away from family, friends and all that is familiar),
Sensory overload (being tethered to noisy machines day and night),
Pain (which may not be adequately controlled in an ICU),
Sleep deprivation,
Disruption of the normal day-night rhythm, or simply
The loss of control over their lives that patients often feel in an ICU.

ICU psychosis often goes away with the coming of morning or sleep. Although it may linger through the day, severe agitation usually occurs only at night. (This phenomenon, called sundowning, is common in nursing homes).