Lack of Sleep may Irreversibly Damage Brain Cells

For most of us, getting the recommended seven to eight hours of shut-eye a night may be--well, next to impossible. Of course, weekends could provide a time to catch up on some much needed rest. However, most of us already know that we can't double up on missed amounts of sleep. In other words, not sleeping at all one day won't necessarily be made up with a 20-hour nap a few days later. Now a recent study also shows that besides feeling groggy, less sleep could irreversibly damage some brain cells used for alertness and cognitive function. 

"In general, we've always assumed full recovery of cognition following short- and long-term sleep loss," said lead study author Dr. Sigrid Veasey, via a press release. "But some of the research in humans has shown that attention span and several other aspects of cognition may not normalize even with three days of recovery sleep, raising the question of lasting injury in the brain. We wanted to figure out exactly whether chronic sleep loss injures neurons, whether the injury is reversible, and which neurons are involved."

As sleep is essential to our bodies, our brains and our overall well-being, researchers studied how these cells might be affected for someone with an unusual work schedule.  

"It's a pretty realistic pattern, [having] three night shifts a week," Dr. Sigrid Veasey, an associate professor of medicine and a member of the Center for Sleep and Circadian Neurobiology at the Perelman School of Medicine at the University of Pennsylvania told FoxNews.com. "It's a realistic amount of sleep loss."

With this information, the researchers studied a group of mice in an environment that mimicked a shift worker's typical sleep pattern. The study showed that short-term sleep loss often led to the damage of the locus coeruleus neurons (LC), otherwise known as a small group of neurons in the brain that are essential for staying awake and cognition. As these LC neurons regulate the sirtuin type 3 (SirT3) protein, an enzyme that manages oxidative stress levels found in the blood, the body also uses mitochondria in order to better generate energy.  

Yet findings showed that after several days of shift worker sleep patterns, the LC neurons in mice began to display reduced SirT3 and increased cell death. In other words, 25 percent of the neurons were lost.

"This is the first report that sleep loss can actually result in a loss of neurons," Veasey notes, via the release.

In particular, he also adds how the findings suggest that mitochondria in LC neurons respond to short-term sleep loss, but not extended waking periods.

Yet findings suggest that mitochondria in LC neurons respond to sleep loss and can adapt to short-term sleep loss but not to extended wake, according to Sleepreviewmag.com. This raises the possibility that somehow increasing SirT3 levels in the mitochondria may help rescue neurons or protect them across chronic or extended sleep loss. The study also demonstrates the importance of sleep for restoring metabolic homeostasis in mitochondria in the LC neurons and possibly other important brain areas, to ensure their optimal functioning during waking hours.

For future studies, researchers hope to examine post-mortem evidence of increased LC neuron loss and production in various neurodegenerative disorders.

More information regarding the study can be found via The Journal of Neuroscience.