The Brain May 'Eat Itself' When Sleep-Deprived

The consequences of sleep deprivation go far beyond needing a cup of coffee to perk you up. Consistently skimping on sleep spurs the brain to begin gobbling neurons and synaptic connections, suggests a new animal study published in the Journal of Neuroscience.

The study went as follows: Researchers led by Michele Bellesi of the Marche Polytechnic University in Italy looked at the brains of mice who could sleep as long as they pleased, who were spontaneously woken up, who were awake an extra eight hours or who were awake for five whole days (chronic deprivation). Specifically, they looked at the mice's glial cells, what New Scientist calls "the brain's housekeeping system."

One type of glial cell – an astrocyte – is meant to rid the brain of extraneous synapses, or connections, in an effort to rewire and rejuvenate it. Another, called a microglial cell, is meant to destroy "old and worn out cells via a process called phagocytosis - meaning 'to devour' in Greek," reports ScienceAlert.

While this may be a regular part of the sleeping process, both of these glial cells proved very active in the study when it came to sleep loss.

For example, sleep-deprived mice had more active astrocytes than did well-rested mice (i.e., 5.7 percent synapse activity in the well-rested brains compared to 13.5 percent in those kept awake for five days). Simply put: The brain appeared to begin eating itself.

"We show for the first time that portions of synapses are literally eaten by astrocytes because of sleep loss," Bellesi told New Scientist.

This process could in theory be a good thing (as Bellesi puts it, the biggest synapses "are like old pieces of furniture"), but the same hyped-up activity occurred in the microglial cells during chronic sleep deprivation as well. Such overactivity in microglial cells could mean a more sinister outlook: brain disorders. "We already know that sustained microglial activation has been observed in Alzheimer's and other forms of neurodegeneration," Bellesi added.

There's been a 50 percent uptick in Alzheimer's deaths since 1999, ScienceAlert points out.

Now, researchers want to explore the effects of sleep deprivation over time. It's unclear if getting more sleep other nights to compensate for sleeplessness could undo previous harm.

At least one study from Harvard Medical School indicates you can't make up for lost sleep time. And one recent study suggests exercise is key to improving sleep.