Actigraphic and Self-reported Sleep Measures in Older Adults: Factor Analytic Study.

Actigraphy has been used to measure older adults' sleep, but few studies have evaluated the factor structure among actigraphy-measured sleep parameters. Additionally, previous studies have reported the association between actigraphy-measured and self-reported sleep parameters in older adults but have not controlled for covariates of gender, insomnia, cognitive impairment, depression, and health conditions. We therefore investigated the factor structure of actigraphy-measured sleep parameters and, controlling for covariates, the association between actigraphy-measured and self-reported sleep parameters in 62 older adults (female: 75.8%; mean age: 69.9). The factor analysis gave a three-factor solution: length of wakefulness during sleep, sleep disruption, and total sleep time. Self-reported sleep parameters and covariates explained actigraphy-measured total sleep time (explained variance: 61%) substantially more than length of wakefulness during sleep (explained variance: 14%) and sleep disruption (explained variance: 11%). Studies need to select sleep measures based on their focus to best understand sleep characteristics in healthy older adults.