1.0 BACKGROUND

ACTIGRAPHY HAS BEEN USED TO STUDY SLEEP/WAKE PATTERNS FOR OVER 20 YEARS. The advantage of actigraphy over traditional polysomnography (PSG) is that actigraphy can conveniently record continuously for 24-hours a day for days, weeks or even longer. In 1995, Sadeh et al., 1 under the auspices of the American Sleep Disorders Association (now called the American Academy of Sleep Medicine, AASM), reviewed the current knowledge about the role of actigraphy in the evaluation of sleep disorders. They concluded that actigraphy does provide useful information and that it may be a “cost-effective method for assessing specific sleep disorders...[but that] methodological issues have not been systematically addressed in clinical research and practice.” Based on that task force’s report, the AASM Standards of Practice Committee concluded that actigraphy was not indicated for routine diagnosis or for assessment of severity or management of sleep disorders, but might be a useful adjunct for diagnosing insomnia, circadian rhythm disorders or excessive sleepiness. 2 Since that time, actigraph technology has improved, and many more studies have been conducted. Several review papers have concluded that wrist actigraphy can usefully approximate sleep versus wake state during 24 hours and have noted that actigraphy has been used for monitoring insomnia, circadian sleep/wake disturbances, and periodic limb movement disorder. 3, 4 This paper begins where the 1995 paper left off. Under the auspices of the AASM, a new task force was established to review the current state of the art of this technology.

Actigraphs are devices generally placed on the wrist (although they can also be placed on the ankle or trunk) to record movement. Collected data are downloaded to a computer for display and analysis of activity/inactivity that in turn can be further analyzed to estimate wake/sleep. The latter technology is based on the observation that there is less movement during sleep and more movement during wake. As described in Ancoli-Israel, 5 the first actigraphs were developed in the early 1970’s. 6-8 Kripke and colleagues were some of the first investigators to publish reliability data on the use of wrist actigraphy for the assessment of sleep. 9-11 Over the years, additional types of actigraphs were developed leading to the digital types used today.