Chronic sleep deprivation could cause the brain to begin “eating itself” – resulting in significant amount of healthy neurons and synaptic connections to being destroyed.

The findings come from a study, led by neuroscientist Michele Bellesi from the Marche Polytechnic University in Italy, which examined mammalian brains and their response to poor sleeping habits.

During normal sleep, a mammal’s brain clears away some of the toxic byproducts of neural activity left behind during the day.

The process, called phagocytosis, involves older neurons in the brain being regularly refreshed and cleared out by microglial cells – the first and main form of immune defense in the central nervous system.

The study – conducted on mice – found that this process of “cleaning up” is accelerated during periods of sleep deprivation, resulting in the brain becoming overactive and clearing out neurons indiscriminately, including new, healthy ones.

For the study, the researchers imaged the brains of four groups of mice. One was well rested (sleep for six to eight hours); another was periodically woken up from sleep; a third group was kept awake for an extra 8 hours (sleep-deprived); and a fourth group was kept awake for five days straight (chronically sleep-deprived).

In the well-rested mice, the cleaning activity was detected in 5.7 percent of brain neurons and in 7.3 of the spontaneously awake mouse brains. In the sleep-deprived mouse brains, activity was a little higher – 8.4 per cent.

In the chronically sleep-deprived mice, however, the activity was significantly higher – 13.5 per cent.

“The results suggest that chronic sleep loss, through microglia priming, may predispose the brain to damage,” the report states.

“Chronic sleep restriction activates microglia, promotes their phagocytic activity, and does so in the absence of overt signs of neuroinflammation.

“This suggests that like many other stressors, extended sleep disruption may lead to a state of sustained microglia activation, perhaps increasing the brain's susceptibility to other forms of damage.”

To download and read the full study, called Sleep Loss Promotes Astrocytic Phagocytosis and Microglial Activation in Mouse Cerebral Cortex click here for the Journal of Neuroscience.