Researchers at the University of Wisconsin have found, through their work with mice, that sleep amplifies the production of cells that produce the insulating material known as myelin, which protects the brain’s circuitry.

The findings, which appeared in the Journal of Neuroscience, could lead to insight on sleep’s role in brain repair, growth, and diseases.  

According to Dr Chiara Cirelli, a lead scientist working on the research, the production rate of the myelin-making cells, immature oligodendrocytes, doubled as mice slept. The increase was most marked during REM, and was driven by genes.

In contrast, the genes involved in cell death and stress responses were turned on when the mice were forced to stay awake.

“For a long time, sleep researchers focused on how the activity of nerve cells differs when animals are awake versus when they are asleep,” Cirelli said in a released statement. “Now it is clear that the way other supporting cells in the nervous system operate also changes significantly depending on whether the animal is asleep or awake.” 

The researchers say their findings suggest that sleep loss might aggravate some symptoms of multiple sclerosis (MS), a disease that damages myelin.