Some rapid eye movement sleep can help you hold on to memories: study

Washington: If you want to hold on to your memories, then hit the sack for some deep sleep as a new study suggests so.

Researchers at the Douglas Mental Health University Institute (McGill University) and the University of Bern provided evidence that rapid eye movement (REM) sleep, the phase where dreams appear, is directly involved in memory formation, at least in mice.

Researcher Sylvain Williams said, "We already knew that newly acquired information is stored into different types of memories, spatial or emotional, before being consolidated or integrated," adding "How the brain performs this process has remained unclear, until now. We were able to prove for the first time that REM sleep is indeed critical for normal spatial memory formation in mice."

To test the long-term spatial memory of mice, the scientists trained the rodents to spot a new object placed in a controlled environment where two objects of similar shape and volume stand. Spontaneously, mice spend more time exploring a novel object than a familiar one, showing their use of learning and recall.

When these mice were in REM sleep, however, the researchers used light pulses to turn off their memory-associated neurons to determine if it affects their memory consolidation. The next day, the same rodents did not succeed the spatial memory task learned on the previous day. Compared to the control group, their memory seemed erased, or at least impaired.

"Silencing the same neurons for similar durations outside REM episodes had no effect on memory. This indicates that neuronal activity specifically during REM sleep is required for normal memory consolidation," said lead author Richard Boyce.

In particular, REM sleep is often significantly perturbed in Alzheimer's diseases (AD), and results from this study suggest that disruption of REM sleep may contribute directly to memory impairments observed in AD, the researchers noted.

The study is published in Science.