How Sleep Helps Memory and Learning

June 29, 2005 -- While you sleep, your brain is busy preparing for the next day.

Its to-do list includes memorizing new skills and filing them for effective use in the morning. Without sleep, it may be tougher to master those new tasks.

That's according to experts from Boston's Beth Israel Deaconess Hospital.

In their study, memory and learning improved with sleep. The findings appear in Neuroscience.

That may be one reason why babies, children, and teens need more sleep than adults. It could also help people recovering from brain injuries, the researchers say.

Memory Test

The study included 12 healthy young adults. They got two lessons in finger-tapping exercises. The task was similar to playing piano scales.

One lesson was done in the morning, followed by a test 12 hours later. The other lesson was done in the evening, with a morning test 12 hours later.

Results were better on the morning test. That may be because subjects had a chance to go home and get a normal night's sleep before the test, say the researchers.

They included Matthew Walker, PhD. He directs the Sleep and Neuroimaging Laboratory at Beth Israel Deaconess Hospital. Walker is also an assistant professor of psychiatry at Harvard Medical School.

The researchers used a brain imaging scan while the subjects were tested. The scans showed different brain-activity patterns after sleep.

Take the lower part of the brain, for instance. One of its jobs includes controlling speed and accuracy. This brain region was "clearly more active when the subjects had had a night of sleep," says Walker in a news release.

Not so for the more central parts of the brain. These systems are involved in stress and emotions like anxiety. These regions were less active after sleep, say the researchers.

Learning in Your Sleep

"The MRI scans are showing us that brain regions shift dramatically during sleep," says Walker.

"When you're asleep, it seems as though you are shifting memory to more efficient storage regions within the brain," he says.

"Consequently, when you awaken, memory tasks can be performed both more quickly and accurately, and with less stress and anxiety," says Walker.

Sleep and Age

Babies, children, and teens need more sleep than adults, says Walker. "Sleep appears to play a key role in human development."

For instance, everything is brand new to infants. They take in an "immense amount of new material," says Walker.

It may take a great deal of sleep to consolidate all that information, he says.

Sleep for Brain Rehab

After brain injuries, including stroke, patients often must learn language and routine tasks all over again.

"Perhaps sleep will prove to be another critical factor in a stroke patient's rehabilitation," says Walker. That wasn't tested in this study.

Don't Count on Catch-Up Sleep

Got a habit of burning the midnight oil during the week? A weekend sleep binge may not make up for it.

"Our research is demonstrating that sleep is critical for improving and consolidating procedural skills," says Walker. "You can't shortchange your brain of sleep and still learn effectively."