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Abstract:
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Actigraphs, wristwatch-like devices that detect body movements and translate movements to digital counts in user-defined time intervals, have long been used in studies of sleep and circadian rhythms. Actigraphy has become increasingly relevant in population-based epidemiologic studies because of its cost-effectiveness, ability to monitor activity for extended periods of time, and validity and reliability. However, for those not directly involved in this line of research, the process involved in actigraphy may appear as a black box with little detail on formulas used for derivation of the sleep parameters. This is in part due to limited literature illustrating the methodology especially for those interested in initiating research in the field. The objectives of this study are to illustrate existing algorithms used to estimate wake/sleep cycles and provide formulas for derivation of parameters that describe sleep quality, quantity, and circadian rhythms. Emphasis is placed on technical definitions and practical interpretations of the parameters. We employ data collected using the Octagonal Micro Sleepwatch from the Buffalo Cardio-Metabolic Occupational Police Stress study.
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