Actografie

Actografie, also known as actigraphy, is a non-invasive method for monitoring human rest-activity cycles using a wearable device, typically worn on the wrist. The device contains an accelerometer that records movement over extended periods, from several days to weeks. The resulting data are summarized into epochs and analyzed with algorithms to estimate periods of sleep and wakefulness, producing variables such as total sleep time, sleep efficiency, sleep onset latency, and wake after sleep onset. Actigraphy provides an indirect measure of sleep by inferring rest periods from absence of movement, rather than measuring brain activity.

In practice, actigraphy is widely used in sleep research and clinical settings where polysomnography is impractical or too burdensome. It enables long-term monitoring in naturalistic environments and is used to assess circadian rhythm disorders, insomnia, pediatric sleep problems, and sleep disturbances in medical or psychiatric conditions. It is also used in occupational health and sports science to study activity patterns and recovery.

Limitations: Actigraphy cannot assess sleep stages; its accuracy depends on the algorithms and device, and it may misclassify quiet wakefulness as sleep or restless sleep as wake. Placement, wearer compliance, and movement characteristics of individuals can affect results. To improve accuracy, actigraphy is often used in combination with sleep diaries or concurrent polysomnography in validation studies.

History: Actigraphy emerged from actimetry in the 20th century and became widely used in the late 1990s and 2000s with commercially available wrist-worn devices. While not a replacement for polysomnography, it provides a practical, ecological tool for sleep and circadian research.