Poor sleep in old age can prevent the brain from storing memories, according to a new study from the University of California, Berkeley.

Neuroscientists from UC Berkeley were able to establish a connection between “deep sleep” and the transition of memories from short-term to long-term centers of the brain.

The research, which was published in the journal Nature Neuroscience, compared pre-sleep and post-sleep memory tests from 18 young people and 15 seniors in relation to their sleep quality—specifically, their quality of slow wave sleep (SWS), the deep sleep period that plays a role in storing memories.

Results showed that seniors’ deep sleep quality was about 75% worse than the deep sleep quality of the younger participants. As a result, seniors’ memory test results were 55% worse than those of the younger participants, according to the study.

By monitoring brain activity during the tests, scientists concluded that the slow brain waves generated during SWS sleep allowed the younger adults to shift memories from the brain’s hippocampus (short-term memory center) to the prefrontal cortex (longer-term memory center).

Because seniors generated less SWS sleep, their memories were “stuck” in the hippocampus and then overwritten by new memories, the findings suggest.

The research helps to explain some of the forgetfulness experienced by the elderly, such as difficulty remembering names, scientists said.

“When we are young, we have deep sleep that helps the brain store and retain new facts and information. But as we get older, the quality of our sleep deteriorates and prevents those memories from being saved by the brain at night,” said Matthew Walker, associate professor of psychology and neuroscience at UC Berkeley.

The results offer scientists new hope to develop treatments that can boost sleep quality for the elderly in order to improve their memory.

“Can you jumpstart slow wave sleep and help people remember their lives and memories better? It’s an exciting possibility,” said Bryce Mander, a postdoctoral fellow in psychology at UC Berkeley.

Scientists from the University of California Berkeley, the California Pacific Medical Center, and the University of California San Diego contributed to the study, which is available on the Nature Neuroscience website.