The Effects of the Nocturnal Sleep on Learning of a Complex Motor Skill in Young and Older Adults.

Background/study context: Research on older adults has shown impairments in nocturnal sleep, impacting motor memory consolidation and learning. However, previous studies primarily focus on simple tasks, limiting generalization to complex motor activities. Moreover, no evidence exists on how sleep influences adaptability and relearning in older adults.

Methods: Sixty older adults and 60 young adults practiced an underarm dart-throwing task. The participants were divided into 2 sub-groups: SLEEP, which practiced in the evening and was retested on the morning of the following day, and CONTROL, which practiced in the morning and was retested in the evening on the same day. The practice and retention phases were spaced 12 hours. We analyzed motor learning through persistence, adaptability and relearning rate.

Results: Sleep did not enhance motor learning for any group. While young adults exhibited retention, older adults did not, especially after nocturnal sleep. There was no difference between sub-groups in adaptability. Older adults demonstrated inferior relearning compared to young adults, independently of sleep.

Conclusion: Nocturnal sleep did not influence memory consolidation in any group. On the contrary, our findings suggest that nocturnal sleep harms retention in older adults. Age-related characteristics induce a worse relearning rate regardless of sleep occurrence.