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Newly developed waist actigraphy and its sleep/wake scoring algorithm

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The purpose of this study was to formulate an algorithm for assessing sleep/waking from activity intensities measured with a waist-worn actigraphy, the Lifecorder PLUS (LC; Suzuken Co. Ltd., Nagoya, Japan), and to test the validity of the algorithm. The study consisted of 31 healthy subjects (M/F = 20/11, mean age 31.7 years) who underwent one night of simultaneous measurement of activity intensity by LC and polysomnography (PSG). A sleep(S)/wake(W) scoring algorithm based on a linear model was determined through discriminant analysis of activity intensities measured by LC over a total of 235 h and 56 min and the corresponding PSG-based S/W data. The formulated S/W scoring algorithm was then used to score S/W during the monitoring epochs (2 min each, 7078 epochs in total) for each subject. The mean agreement rate with the corresponding PSG-based S/W data was 86.9%, with a mean sensitivity (sleep detection) of 89.4% and mean specificity (wakefulness detection) of 58.2%. The agreement rates for the individual stages of sleep were 60.6% for Stage 1, 89.3% for Stage 2, 99.2% for Stage 3 + 4, and 90.1% for Stage REM. These results demonstrate that sleep/wake activity in young to middle-aged healthy subjects can be assessed with a reliability comparable to that of conventional actigraphy through LC waist actigraphy and the optimal S/W scoring algorithm.
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Keywords: actigraphy; polysomnography; sleep-waking; sleep/wake scoring algorithm; waist-worn

Document Type: Research Article

Affiliations: 1: Aoki Hospital, Clinical Laboratory, Tokyo, 2: Central Research Insitute of Electric Power Industry, Materials Science Research Laboratory, Tokyo, 3: Kissei Comtec Co. Ltd., Nagano, 4: Department of Psychophysiology, National Institute of Mental Health, National Center for Neurology and Psychiatry, Tokyo, 5: Department of Life Sciences and Bio-informatics, Graduate School of Allied Health Sciences, Tokyo Medical and Dental University, Tokyo, 6: Aino University, Osaka, Japan

Publication date: January 1, 2009

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