Impaired off-line motor skills consolidation in young primary insomniacs.

Compelling evidence indicates that sleep can facilitate the off-line consolidation of declarative, perceptual, emotional and procedural memories. Here we assessed the sleep-related off-line consolidation of motor skills in 13 young primary insomniacs (23.31±2.5 yrs) compared to 13 healthy sleepers (24.31±1.6 yrs) using the sequential finger tapping task. During a training session insomniacs performed less correct sequences than controls. However, both groups exhibited similar on-line motor learning in the pre-sleep evening session. After a night of sleep, healthy controls improved their performance, indicating an overnight effect of sleep on motor skills consolidation. In contrast, insomniacs failed to exhibit a sleep-related enhancement in memory performance indicating impairment in the off-line motor skills consolidation process. Our results suggest that young adults with insomnia experience impaired off-line memory consolidation which seems not to be associated with reduced ability to acquire new motor information.