Sleep, not just practice, is critical to learning skilled-movement tasks, US scientists have discovered, writes Esther Ingram.
In a study at Harvard Medical School, adults were trained either in the morning or the evening to perform a skilled finger-movement task such as playing a piano scale.
The researchers found that people who trained in the morning and then practised again in the evening showed no significant improvement in the task. But those who trained in the evening and had a night's sleep showed remarkable gains in speed and accuracy of playing the following morning.
The researchers conclude that our brain continues to learn new skills even when we finish practicing them but only while we sleep. Furthermore, they found a critical period of sleep for learning the task. Most of the overnight improvement in performance was determined by the last two hours of sleep, the light non-rapid eye movement phase. People getting a lot of this sleep improved most at the task the following day.
Matthew Walker, lead author of the study published in Learning and Memory , said: "Modern life's erosion of sleep time, particularly with early-morning starts, could seriously be short-changing our brain's learning potential.
"Learning skilled actions may require a good night's sleep before the maximum benefit of that practice is achieved."
The study also found that if people were retested after several nights' sleep, they showed even more improvement in the task.
"Although there may be a point where the skill is so well learnt that sleep does not improve it any more, sleeping may be critical in maintaining that performance level, together with continued task engagement," Dr Walker said.
The authors said that this research suggested that children needed to sleep a lot to consolidate new experiences and skills acquired during an intense learning period.