Table 1.

Definition of sleep parameters

Sleep parameters	Definition
Total sleep time (TST)	Time in minutes from sleep onset to sleep offset less the wake time; equal to the total of all REM and NREM sleep
Wake after sleep onset (WASO)	Periods of wakefulness occurring after defined sleep onset
Light sleep	The first and second stages of NREM sleep during which the heart rate slows and body temperature decreases
Deep sleep	The third stage of NREM sleep during which more slow-wave is observed and individuals have high awakening threshold to nonsignificant stimuli
REM sleep	A stage of sleep characterized by rapid eye movements and associated with dreaming
Number of awakenings (NAWK)	The number of awakenings occurring after defined sleep onset
Sleep onset latency (SOL)	Time in minutes from “light out” to the first epoch scored as sleep
Sleep efficiency (SE)	Percentage of total time in bed spent in sleep