Table 2.

Sleep–wake indices.

Sleep variable	Definition (units)
Total sleep time	Actual time spent asleep from sleep start and end, minus any wake time (hours: mins [hm])
Time in bed	Difference between bedtime and awakening time (hm)
Sleep onset latency	The time it takes to transition from full wakefulness to sleep onset (hm)
Wake after sleep onset	The total number of hours and mins marked awake after sleep onset (hm)
Sleep efficiency	The sleep duration expressed as a percentage of time asleep from bedtime to wake (%)
Sleep fragmentation index	A measure of restlessness based on physical movement and expressed as a percentage (%)

A description of the sleep indices collected from the wearable technology used in both study 1 and 2.