We don’t know why we sleep, yet we can all attest to the miserable consequences we experience when we don’t get enough of it. There's only so much coffee can do. Indeed, our lives depend on sleep, and we’re beginning to understand more reasons why. This week researchers at the University of Wisconsin, Madison uncovered another critical function of sleep: It boosts myelin production.
Scientists examined mice that were either well rested or sleep deprived, and analyzed the gene expression of cells that produce myelin. They found these genes were turned on during sleep, thus promoting myelin production. Conversely, these genes were turned off during wakefulness, and genes involved in the stress response and apoptosis, or cell death, were turned on. Sleep deprivation is more than just a condition — it shuts down repair and increases damage.
Myelin, the material found, is a type of glial cell. Glia make up almost 90% of our brain cells and provide support, nutrients, and repair to neurons. Mostly made of fat, myelin is an electrical conductor in the nervous system. It wraps around and insulates axons, the long projections extending from neurons that carry electrical signals from one cell to another. Myelin is essential to proper nervous system function, and damage can lead to immobility or loss of vision as seen in the disease Multiple Sclerosis (MS).
Interestingly, myelin production almost doubled during rapid eye movement (REM) sleep, when dreams occur. Previous studies have shown that REM sleep and dreams may also play a role in learning and memory. This is another indication of the benefits of sustained, uninterrupted sleep.
It's important to remember that this research was done in mice and not humans. However, the results still reveal how behavior can influence gene expression. Moreover, it demonstrates sleep’s role in brain health, and the detrimental effects of too little. Future studies may examine the association between sleep deprivation and MS, and if deprivation worsens MS symptoms.
Usually in the shadow of neurons, glia have finally received their long overdue attention over the last few years. Scientists discovered they do much more than just support neuron function. They may actually be active participants in the neuron firing and control communication between neurons. As this study confirms, glia are just as important as neurons, and they’re both affected by sleep.
Sleep deprivation does more than just make us drowsy — it can actually harm our brains. Since we’ll spend one-third of our lives asleep, understanding how it can repair or damage the brain is essential. As scientists continue to discover the many functions of sleep, this gives you yet another reason to press snooze.
Findings were published in September 4 issue of The Journal of Neuroscience.