A Deeper Sleep

Regions of the brain that have spent the day learning sleep more heavily at night.

In a study published in the journal Nature, Giulio Tononi, a psychiatrist at the University of Wisconsin-Madison, had subjects perform a simple point-and-click task with a computer adjusted so that its cursor didn't track in the right direction. Afterwards, the subjects' brain waves were recorded while they slept, then examined for "slow wave" activity, a kind of deep sleep.

Compared to people who'd completed the same task with normal cursors, Tononi's subjects showed elevated slow wave activity in brain areas associated with spatial orientation, indicating that their brains were adjusting to the day's learning by making cellular-level changes. In the morning, Tononi's subjects performed their tasks better than they had before going to sleep.