Screening Instruments of Sleep Disorders: Actigraphy

Abstract

Wrist actigraphy is based on the premise that little movement occurs during sleep, but that activity increases when awake. Wrist actigraphy has the advantages of being cost efficient and allowing the recording of sleep in the natural environment. In addition, it can record continuous behavior for 24 h a day, 7 days a week. Although actigraphy is not a replacement for electroencephalography or polysomnography, there are times when it provides clear advantages for data collection. Actigraphy is particularly useful for studying individuals who cannot tolerate sleeping in a laboratory, for example small children and older adults. It may provide a more accurate estimate of typical sleep duration by providing an opportunity for patients to adhere more closely to their habitual sleep environments. Actigraphy is also becoming an important tool in follow-up studies, and for examining efficacy in clinical outcomes. It has some value in the assessment of sleep disorders, although it may not help in distinguishing between different sleep disorders. Newer scoring algorithms have great accuracy in determining the variables that are most important in insomnia – that is, they have improved ability to detect wake versus sleep, sleep latency, awakenings during the night, and total sleep time. Actigraphy is superior to a subject’s self-reported sleep logs, particularly in detecting brief arousals during the night. It can also be used for the evaluation and clinical diagnosis of circadian rhythm disorders. The ability to detect movement holds promise for the identification of sleep disorders characterized by frequent movements, such as periodic limb movements during sleep, sleep apnea, or rapid eye movement sleep behavior disorders. Traditionally, the actigraphs are placed on the non-dominant hand, and the data collected is displayed on a computer and examined for activity/inactivity and analyzed for wake/sleep cycles. This chapter will review the development of actigraphy, the major areas where it can be used, tips for its successful use, and its limitations.