Validity of Actigraphy in Young Adults With Insomnia

Objective/Background: Actigraphy is an inexpensive and objective wrist-worn activity sensor that has been validated for the measurement of sleep onset latency (SOL), number of awakenings (NWAK), wake after sleep onset (WASO), total sleep time (TST), and sleep efficiency (SE) in both middle-aged and older adults with insomnia. However, actigraphy has not been evaluated in young adults. In addition, most previous studies compared actigraphy to in-lab polysomnography (PSG), but none have compared actigraphy to more ecologically valid ambulatory polysomnography. Participants: 21 young adults (mean age = 19.90 +/- 2.19 years; n = 13 women) determined to have chronic primary insomnia through structured clinical interviews. Methods: Sleep diaries, actigraphy, and ambulatory PSG data were obtained over a single night to obtain measures of SOL, NWAK, WASO, time spent in bed after final awakening in the morning (TWAK), TST, and SE. Results: Actigraphy was a valid estimate of SOL, WASO, TST, and SE, based on significant correlations (r = 0.45 to 0.87), nonsignificant mean differences between actigraphy and PSG, and inspection of actigraphy bias from Bland Altman plots (SOL alpha = 1.52, WASO alpha = 7.95, TST alpha = -8.60, SE alpha = -1.38). Conclusions: Actigraphy was a valid objective measure of SOL, WASO, TST, and SE in a young adult insomnia sample, as compared to ambulatory PSG. Actigraphy may be a valid alternative for assessing sleep in young adults with insomnia when more costly PSG measures are not feasible.