actigraph

Actigraph is a device or method used to monitor activity over time, typically by recording motion with a small accelerometer worn on the body. Most actigraphs are placed on the wrist, ankle, or another body location and translate movement into digital activity counts. Data are commonly processed in fixed time intervals, or epochs, such as one minute, to produce activity-rest profiles.

In clinical and research settings, actigraphy is used to estimate sleep-wake patterns, circadian rhythms, and overall activity levels across days to weeks. It is less invasive and more convenient than polysomnography, allowing for ambulatory monitoring outside specialized laboratories. Actigraphy is widely used in sleep medicine to assess circadian rhythm disorders and insomnia, as well as in pediatric sleep evaluation and fatigue assessment in various professional and clinical populations.

Actigraphy also finds applications in animal studies to monitor locomotor activity and daily activity patterns. Advantages of actigraphy include objectivity, continuous data collection, and ease of use for long monitoring periods. Limitations include the inability to directly determine sleep stages, potential misclassification of quiet wake as sleep, sensitivity to device placement and chosen analysis algorithms, and reliance on participant compliance and diary records for optimal interpretation.

Overall, actigraphy provides continuous, objective activity data that complements more comprehensive measures such as sleep diaries and polysomnography, supporting assessment of sleep, circadian biology, and activity-related health outcomes.