Table 1.

Explanation of sleep variables extracted from the actiwatch

Sleep variable	Explanation	Measure
Bedtime	The time participant went to bed with the intent to sleep	Time
Rise time	The time participant got up and started the day	Time
Sleep onset latency	Period of time between bedtime and sleep initiation	Minutes
Time in bed (sleep period)	Time between bed time and rise time	Hours
Sleep interval duration	Time between sleep start and sleep end	Hours
Awakenings	Number of awakenings during the sleep interval	Number
Average duration of awakenings	Average duration of blocks scored as wake (awakenings)	Minutes
WASO	Wake after sleep onset — the number of waking minutes between sleep start and sleep end	Minutes
Percentage mobility	Percentage of time scored as mobile in the sleep interval	Percentage
Sleep efficiency	Percentage of time in bed actually spent sleeping	Percentage