Table 1.

Description of Sleep Measures

Measure	Description
Latency	Sleep latency is the time it takes to fall asleep, as measured by the difference between bedtime and the onset of sleep (measured in minutes).
Efficiency	Sleep efficiency is the number of minutes scored as being asleep divided by the total number of minutes in bed. 85% sleep efficiency is typically considered normal sleep efficiency, so higher values indicated better sleep for the amount of time spent in bed.
Total minutes	Total minutes spent in bed.
Total sleep time	Total sleep time is the number of minutes scored as being asleep.
WASO	Wake after sleep onset (WASO) is the total number of minutes awake after the initial onset of sleep. Larger values indicate poorer sleep.
Awakening frequency	The number of different awakening episodes after the initial onset of sleep. Higher values indicate more awakenings and poorer sleep.
Average awakening length	The average length, in minutes, of all awakening episodes. Higher values indicate greater time spent awake for each awakening episode, which reflects poorer sleep.
Movement index	The movement index is the percentage of epochs with y-axis counts greater than zero in the sleep period. Thus higher values indicate more movement and suggest less restful sleep.
Fragmentation index	The fragmentation index is a measure of restlessness and interruption of sleep. It is calculated by the percentage of one minute sleep periods versus all sleep periods. Higher values indicate more frequent interruption of sleep (and, therefore, poorer sleep).
Sleep fragmentation index	The sum of the movement and fragmentation indices. Higher values suggest greater microarousals and poorer sleep quality.
Poor sleep factor	CFA-derived factor score summarizing poor sleep quality using the total actigraphy counts summed together over the sleep period, efficiency, WASO, average awakening length, movement index, and sleep fragmentation.

Source: Authors’ compilation.