In<unk>  science,<unk>  <unk>  is the length of time that it takes to accomplish the transition from full wakefulness to<unk> , normally to the lightest<unk>  stage non-REM.
Daytime tests, such as the MSLT, measure<unk>  as an indication of excessive daytime<unk> iness (EDS).  A<unk>  of 15-25 minutes in a person's biological daytime is considered normal. A shorter<unk>  is likely a sign that a person suffers from<unk>  deprivation.  A<unk>  of less than five minutes indicates either very unhealthy daytime<unk> iness or one of several<unk>  disorders, for example narcolepsy.
A long<unk>  at bedtime can be an indication of a<unk>  disorder, including but not limited to insomnia.
Sleep onset latency
Rapid eye movement sleep
Insomnia diagnostic criteria
Face time
Postictal state
Cognitive reserve
Basal metabolic rate
Non-24-hour sleep-wake syndrome