Sleep Optimizes Motor Skill in Older Adults

OBJECTIVES To determine whether sleep benefits motor memory in healthy elderly adults and, if so, whether the observed sleep-related benefits are comparable with those observed in healthy young adults. DESIGN Repeated-measures cross-over design. SETTING Boston, Massachusetts (general community) and Harvard University. PARTICIPANTS Sixteen healthy older and 15 healthy young participants. MEASUREMENTS Motor sequence task (MST) performance was assessed at training and at the beginning and end of the retest session; polysomnographic sleep studies were recorded for the elderly participants. RESULTS After 12 hours of daytime wakefulness, elderly participants showed a dramatic decline in MST performance on the first three retest trials, and only a nonsignificant improvement by the end of retest (the last 3 retest trials). In contrast, when the same participants trained in the morning but were retested 24 hours after training, after a day of wake plus a night of sleep, they maintained their performance at the beginning of retest and demonstrated a highly significant 17.4% improvement by the end of the retest session, essentially identical to the 17.3% improvement seen in young participants. These strikingly similar improvements occurred despite the presence of other age-related differences, including overall slower motor speed, a lag in the appearance of sleep-dependent improvement, and an absence of correlations between overnight improvement and sleep architecture or sleep spindle density in the elderly participants. CONCLUSION These findings provide compelling evidence that sleep optimizes motor skill performance across the adult life span.