Naps with stages spark learning

Napping shows potential as a way to stimulate learning, at least for volunteers performing a laboratory task that requires visual discriminations. There’s a catch, though, say psychologist Sara Mednick of Harvard University and her colleagues. Only naps consisting of both slow-wave sleep and rapid-eye movement (REM) sleep inspire improved performance on the task.

In fact, the volunteers’ speed in accurately doing the task increased as much after taking a 90-minute nap that contained both sleep stages as had previously been observed for people granted a full night’s slumber (SN: 7/22/00, p. 55: Available to subscribers at Sleepers yield memorable brain images). The findings appear in the July Nature Neuroscience.

In the study, 73 volunteer participants spent 1 hour in the morning learning to identify the orientation of three bars flashed in the lower left quarter of a computer screen against a background of horizontal bars.

In the afternoon, 26 of the volunteers took a 60-minute nap and another 19 snoozed for 90 minutes. The rest went without a nap.

When tested that evening, the 30 nappers who had displayed both sleep stages–as determined by brain wave measurements–required less time to make the same visual discriminations that they had made in the morning. The other nappers took slightly longer to execute the task than they had before.

Performance plummeted among those who hadn’t napped.

Two-stage nappers maintained their superiority on the task when tested the next morning, after all participants had had a night’s sleep.

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