Objective sleep assessment is needed to diagnose sleep disorders. The gold standard, Polysomnography (PSG-medical code 95810 or 95811), consists of an overnight study in a sleep lab in which patients come to a sleep laboratory where multiple channels of data are collected including: measures of total sleep time (TST); sleep efficiency (SE); wake after sleep onset (WASO); sleep architecture; and identification of pathological events, including apneas, hypopneas, and periodic leg movements. Advances in PSG equipment have made the collection of these data in their usual sleeping environment, this is the exception. Whether in the sleep lab or home, the collection of PSG data is invasive, disruptive to sleep, and costly (ranging from $1200 to $8,000 in a recent 2013 assessment).
Actigraphy utilizes a single channel that collects motion data, which is used to infer time spent asleep and wake.
Actigraphy is less invasive, less expensive, and the Actigraphy can be worn for extended periods of time in the natural sleep setting. Actigraphy performed over multiple nights may provide more reliable data on sleep measures than PSG, which is typically performed for only one night. Actigraphy data, usually averaged over several nights, typically includes (TST), (SE), (WASO), information about daytime inactivity, and circadian rhythm data. Many prior studies have compared PSG to Actigraphy. These studies have used different actigraph systems, making direct comparison of devices difficult, as patterns of activity and rest may differ and influence the overall accuracy of specific algorithms for inferring sleep. Population differences in age, gender, and morbidity also influence the accuracy of differing approaches. Sleep duration and quality are important predictors of health outcomes, with growing recognition of the importance of sleep in geriatric populations. It is stated that sleep and sleep quality have profound impact on daily life and quality of life. Sleep, as a part of circadian rhythm, plays an essential role on the general health of elders and is associated with depression. There is a need to identify the optimal approaches for measuring sleep parameters in older populations. Poorer Actigraphy reliability in older adults may be attributable to less activity, which may be misinterpreted as sleep by the wrist-worn Actigraphy, or sleep may be underestimated due to the more frequent nocturnal arousals experienced by elders.
Recent development of body worn sensors has allowed less obtrusive monitoring of sleep, and may provide additional data as they measure activity in three dimensions (three planes: vertical, frontal and lateral), in addition to ECG, and Heart and Respiratory Rate, which are wirelessly transmitted and recorded, and may be readily collected in the natural home setting over a series of days.