Concordance of polysomnographic and actigraphic measurement of sleep and wake in older women with insomnia

Abstract

Study Objectives: The objective of this secondary analysis was to evaluate concurrent validity of actigraphy and polysomnography (PSG) in older women with insomnia. Methods: Concurrent validity of actigraphy and PSG was examined through (1) comparison of sleep outcomes from each recording method; (2) calculation of sensitivity, specifi city, accuracy, and predictive values from epoch-by-epoch data; and (3) statistical and graphical exploration of the relationship between sleep disturbance severity and concordance of actigraphy and PSG. Subjects were 16 community-dwelling older women (mean age 69.4 ± 8.1) with insomnia who underwent 8 nights of concurrent actigraphy and PSG. Results: Sleep effi ciency refl ected much greater sleep disturbance on PSG (66.9%) than actigraphy (84.4%). Based on generalized linear models, the parameter estimates for agreement between actigraphy and PSG were statistically signifi cant (p < 0.05) for total sleep time and sleep latency, verged on signifi cance for WASO (p = 0.052), but was not signifi cant for sleep effi ciency (p = 0.20). Epoch-by-epoch analysis showed high sensitivity (96.1%), low specifi city (36.4%), and modest values on agreement (75.4%) and predictive values of sleep (74.7%) and wake (80.2%). Generalized linear models showed that overall accuracy of actigraphy declined as sleep effi ciency declined (unstandardized Beta = 0.741, p < 0.001). Based on this model, sleep effi ciency of 73% was the point at which accuracy declined below an acceptable accuracy value of 80%. Conclusions: Actigraphy offers a relatively inexpensive and unobtrusive method for measuring sleep, but it appears to underestimate sleep disturbance, particularly at sleep effi ciency levels below 73%, in older women with insomnia.