Sleep characteristics were measured using an actigraphy watch, the Octagonal Motionlogger Sleep Watch-L (Ambulatory Monitoring Inc, Ardsley, New York), for 2 consecutive nights during the time that salivary specimens were collected. It was worn on the participants’ nondominant wrist to derive movement-based estimates of sleep-wake characteristics. The actigraph unit was set to 1-minute epoch and zero-crossing mode. We used the Action W-2 software and the Cole-Kripke algorithm (Ambulatory Monitoring Inc, Ardsley, New York) to analyze the sleep data. A previous study has shown good reliability and validity with a reasonable sensitivity higher than 0.60 in polysomnography-actigraphy comparison.18 (link)
For sleep characteristics, time in bed, sleep efficiency (SE), wake after sleep onset (WASO), and mean wake episode during sleep (MWE) were obtained indicating total minutes in bed for nocturnal sleep, percentage of actual sleep at night, total wake minutes during nocturnal sleep, and mean duration of wakes during sleep, respectively. Average values of the 2 nights were used for all the sleep characteristics.
For sleep characteristics, time in bed, sleep efficiency (SE), wake after sleep onset (WASO), and mean wake episode during sleep (MWE) were obtained indicating total minutes in bed for nocturnal sleep, percentage of actual sleep at night, total wake minutes during nocturnal sleep, and mean duration of wakes during sleep, respectively. Average values of the 2 nights were used for all the sleep characteristics.