Want to improve your brain? Sleep on it. A new study found that the act of sleeping increases the reproduction of a substance called myelin, which helps to insulate nerve cell projections in the brain and spinal column. The study, published Sept. 4 in the Journal of Neuroscience, was conducted on mice, so it may or may not have relevance to humans. But the authors, all from the University of Wisconsin-Madison, say the findings could lead to future insights about how sleep helps humans to repair and grow their brains.

The study focused on cells called oligodendrocytes, which produce myelin. Myelin helps to enable electrical impulses to move from one nerve cell to another. More myelin tends to be produced after the brain experiences an injury, but the exact mechanism that turns on that production was unknown until now.

In their study, the researchers took some mice and forced them to stay awake. Another group of mice was allowed to sleep naturally. The researchers then measured the activity of genes in the oligodendrocytes. They found that the genes within the oligodendrocyte cells "turned on" while the mice were asleep. This is consistent with previous studies which found that genes were active at different levels depending on if a brain was asleep or awake.

Perhaps more importantly, they found that genes linked to cell death and cellular stress responses were turned on while the mice were 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," study co-author Chiara Cirelli, a doctor with the university's Center for Sleep and Consciousness, said in a press release. "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 research may have relevance not just for healthy people but those suffering from multiple sclerosis. MS itself damages myelin. Chronic sleeplessness, then, may in turn aggravate some of the symptoms of MS by further hindering the production of myelin.

These findings tie into the work at Cirelli's laboratory, which is looking into the broader functions of sleep and the functional consequences of sleep loss.

In related news, a study published Aug. 21 in the journal Neuron also looked at mice and sleep. They found that a protein called 4E-BP1 blocks the synthesis of certain other proteins. When the 4E protein was removed, the mice were better able to respond to disruptions in their circadian rhythm. The authors, with McGill University and Concordia University, equated this with the ability to recover from jet lag.

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