Studies, which include laboratory investigations (Category I) and field evaluations (Category II and Category III) of population groups that are analogous to astronauts (e.g., medical and aviation personnel), provide compelling evidence that working long shifts for extended periods of time contributes to sleep<unk>  and can cause performance decrements, health problems, and other detrimental consequences, including accidents, that can affect both the worker and others.
Effects of sleep deprivation in space
Free-running sleep
Effects of meditation
Sleep-talking
Sleep state misperception
Non-24-hour sleep–wake disorder
Twilight sleep
Irregular sleep–wake rhythm