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. Author manuscript; available in PMC: 2022 Jun 26.
Published in final edited form as: Sleep Epidemiol. 2021 Nov 25;1:100016. doi: 10.1016/j.sleepe.2021.100016

Figure 1: A graphical display of terminology used in this report for measuring sleep duration and sleep timing.

Figure 1:

Notes.

Items in black font refer to event times (e.g., time into bed) while items in blue font refer to durations (dark blue: sleep onset latency; light blue: sleep durations or time spent with the intention to sleep).

The diagram represents a sleep schedule with a nap lasting approximately 45 minutes at approximately 3:30pm, first attempt to sleep at approximately 10:30pm and a fall asleep time of 10:45pm. This schedule also outlines a wake time of approximately 7:00am and a time out of bed at approximately 7:30am.

This review distinguishes between studies with different “event definitions” of sleep, such as nocturnal and 24-hour sleep. For instance, a researcher interested in capturing 24-hour sleep may combine nap and major sleep episode durations.