Abstract
INTRODUCTION: Sleep disturbances are prevalent in Alzheimer’s disease (AD), but it is currently not known whether night-to-night variation in sleep predicts day-to-day variation in vigilance, cognition, mood, and behavior (daytime measures).
METHODS: Subjective and objective sleep and daytime measures were collected daily for two weeks in 15 participants with mild AD, 8 mild cognitive impairment (MCI) and 22 with no cognitive impairment (NCI). Associations between daytime measures and four principal components of sleep (duration, quality, continuity and latency) were quantified using mixed-model regression.
RESULTS: Sleepiness, alertness, contentedness, everyday memory errors, serial subtraction and behavioral problems were predicted by at least one of the components of sleep, and in particular sleep duration and continuity. Associations between variation in sleep and daytime measures were linear or quadratic and often different in AD from NCI.
DISCUSSION: These findings imply that daytime functioning in AD may be improved by interventions that target sleep continuity.