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.