Lack of sleep can damage memory, researchers point out.

As little as five hours of sleep deprivation can bring on the kind of physical changes that lead to memory loss, according to a study conducted in the Netherlands and Pennsylvania.

Research published in the journal eLife shows that keeping mice awake too long ruins connectivity between neurons in the hippocampus, a region of the brain associated with learning and memory.

The study was intended to reveal how lack of sleep hurts memory formation.

The researchers examined the influence of sleep loss on dendrites, nerve cells that branch out to receive impulses from other cells. They found sleep deprivation significantly reduced the length and spine density of the dendrites in a mouse’s hippocampus.

After three hours of undisturbed sleep, the mice’s dendrites appeared normal again.

The researchers also investigated the increased activity of the protein cofilin, a molecular mechanism that can be blocked to overcome memory-sapping side effects. That finding could be critical to nurses and others who have trouble sleeping due to shift work.

“What is perhaps most striking is that these neuronal connections are restored with several hours of recovery sleep,” says senior author Ted Abel, Ph.D., from the University of Pennsylvania. “When subjects have a chance to catch up on much-needed sleep, they are rapidly remodeling their brain.”