Extra sleep may help restore memory

An extra three to four hours of sleep daily over as little as two days has been found to restore memories in fruit flies with Alzheimer's-like condition.

The findings have implications for humans as according to the researchers brain mechanisms that control sleep in fruit flies are similar to those seen in people.

Studying three groups of flies, the scientists interfered with their ability to remember by disabling a different critical memory gene in each group.

In one group, the disabled gene led the flies to develop a condition with similarities to Alzheimer's disease.

In another group, the disabled gene made it difficult for fly brain cells to reinforce new connections that encode memories. In the third group, the disrupted gene left the flies with too many of these connections.

"Our data showed that extra sleep can handle any of these problems," said senior author Paul Shaw, associate professor of neurobiology at the Washington University School of Medicine in St. Louis.

"It has to be the right kind of sleep, and we are not sure how to induce this kind of slumber in the human brain yet, but our research suggests that if we can learn how, it could have significant therapeutic potential," Shaw pointed out.

As part of the new study, the scientists restored memory in each group of flies by using one of three techniques to increase sleep.

They stimulated a cluster of key brain cells, boosted the production of a protein linked to sleep or gave the flies a drug that mimicked the activity of an important chemical messenger.

Regardless of the technique used to increase sleep, the added slumber -- an extra three to four hours of sleep daily over as little as two days -- restored the flies' ability to make memories.

Sleep helps the brain reinforce connections between brain cells that encode important memories and cut back connections that encode useless information, the researchers said.

The study appeared online in the journal Current Biology.