Actigraphy

Actigraphy uses a wrist-worn accelerometer to infer sleep-wake states from movement patterns over days to weeks, providing an ambulatory and low-burden alternative to polysomnography for longitudinal sleep assessment. Validated algorithms translate raw activity counts into estimates of total sleep time, sleep efficiency, sleep-onset latency, and waking after sleep onset. It is recommended by the American Academy of Sleep Medicine for evaluating insomnia, circadian rhythm disorders, and treatment response in naturalistic settings. Actigraphy systematically overestimates total sleep time and sleep efficiency relative to PSG, particularly in patients with insomnia, and cannot reliably stage sleep.