Table 1.

Sleep Constructs

Construct	Definition/ Calculation
Average Weekly Sleep Duration	Average hours per night of sleep over one week.
Bedtime	The time one falls asleep; when using actigraphy data, defined as the first minute of a five-minute period of no actigraphy-detected period of activity (6).
Bedtime Shift	The absolute difference in weekend and weekday bedtime, calculated as average weekend bedtime minus average weekday bedtime (7).
Sleep Midpoint	Halfway between sleep onset and wake time (12).
Social Jet Lag	Calculated as the absolute difference between the midpoint of nightly sleep on the weekends and midpoint of sleep on weekdays (12).
Waketime	The time one awakens; when using actigraphy data, defined as the first minute of a five-minute period of actigraphy-detected after a period of inactivity (6).
Waketime Shift	The absolute difference in weekend and weekday waketime calculated as average weekend waketime minus average weekday waketime (7).
Weekday Sleep	Average hours per night of sleep over Sunday night through Thursday night sleep (11).
Weekend Catch-Up Sleep	The difference between average hours per night of weekend sleep and weekday sleep; calculated as average hours per night of weekend (Friday and Saturday nights) sleep minus average hours per night of weekday (Sunday through Thursday nights) sleep (11).
Weekend Sleep	Average hours per night of sleep over Friday and Saturday nights’ sleep (6).
Within-Subject Sleep Duration Variability	Night-to-night variation in hours of sleep from the average; calculated in hours as the intra-subject standard deviation of average nightly sleep duration across a multi-day period (9).