Actigraphy

Actigraphy is a non-invasive method of monitoring human rest/activity cycles. A small actigraph unit, also called an actimetry sensor, is worn for a week or more to measure gross motor activity. The unit is usually, in a wrist-watch-like package, worn on the wrist. The movements the actigraph unit undergoes are continually recorded and some units also measure light exposure. The data can be later read to a computer and analysed offline; in some brands of sensors the data is transmitted and analysed in real time.

Sleep actigraphs are generally watch-shaped and worn on the wrist of the non-dominant arm. They are useful for determining sleep patterns and circadian rhythms and may be worn for several weeks at a time. In the medical setting, traditional polysomnography has long been cited as "the 'gold standard' for sleep assessment." Since the 1990s, however, actigraphy has increasingly been used to assess sleep/wake behavior. Studies have found actigraphy to be helpful for sleep research because it tends to be less expensive and cumbersome than polysomnography. Unlike polysomnography, actigraphy allows the patient to be movable and to continue her or his normal routines while the required data is being recorded in his or her natural sleep environment; this may render the measured data more generally applicable. As sleep actigraphs are more affordable than polysomnographs, their use has advantages, particularly in the case of large field studies.

Actigraphy is useful for assessing daytime sleepiness in place of a laboratory sleep latency test. It is used to clinically evaluate insomnia, circadian rhythm sleep disorders, excessive sleepiness and restless legs syndrome. It is also used in assessing the effectiveness of pharmacologic, behavioural, phototherapeutic or chronotherapeutic treatments for such disorders. The data, recorded over time, is in some cases more relevant than the result of polysomnography, particularly in assessing circadian rhythms and disorders thereof as well as insomnia.

...
Wikipedia