Sleep detection with an accelerometer actigraph: comparisons with polysomnography.
Two validation studies were conducted to optimize the sleep-detection algorithm of the Actillume. The first study used home recordings of postmenopausal women (age range: 51 to 77 years), which were analyzed to derive the optimal algorithm for detecting sleep and wakefulness from wrist activity data, both for nocturnal in-bed recordings and considering the entire 24 h. The second study explored the optimal algorithm to score in-bed recordings of healthy young adults (age range: 19 to 34 years) monitored in the laboratory. In Study I, the algorithm for in-bed recordings (n=39) showed a minute-by-minute agreement of 85% between Actillume and polysomnography (PSG), a correlation of.98, and a mean measurement error (ME) of 21 min for estimates of sleep duration. Using the same algorithm to score 24-h recordings with Webster's rules, an agreement of 89%, a correlation of.90, and 1 min ME were observed. A different algorithm proved optimal to score in-bed recordings (n=31) of young adults, yielding an agreement of 91%, a correlation of.92, and an ME of 5 min. The strong correlations and agreements between sleep estimates from Actillume and PSG in both studies suggest that the Actillume can reliably monitor sleep and wakefulness both in community-residing elderly and healthy young adults in the laboratory. However, different algorithms are optimal for individuals with different characteristics.
Jean-Louis
G
G
Department of Psychiatry, University of California San Diego, 9500 Gilman Dr., San Diego, CA 92093, USA. jeanlouisg@yahoo.com
Kripke
D F
DF
Cole
R J
RJ
Assmus
J D
JD
Langer
R D
RD
D000328:Adult; D000368:Aged; D000465:Algorithms; D002138:Calibration; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D017286:Polysomnography; D012890:Sleep / Q000502:physiology*