Does sleep deprivation really cause the brain to eat itself?

Our brain starts to ‘eat itself’ when we are deprived of sleep, researchers at the Marche Polytechnic University in Italy have found.

According to a study published in The Journal of Neuroscience, cells in the brain that are in charge of ‘housekeeping’ — or destroying worn-out cells and circuitry — go into overdrive following sleep deprivation. This phenomenon was only observed in mice.

The researchers found that after undisturbed sleep, these cells, known as astrocytes, were active in about six per cent of the brain’s synapses in the subject rodents. In those that were sleep deprived, this figure increased to 13.5 per cent.

The results suggest that sleep deprivation can cause the brain to break down more of its connections in the large synapses than it would under normal circumstances.

The research does not establish if this is harmful to the brain. ‘[The largest synapses] are like old pieces of furniture, and so probably need more attention and cleaning,’ the study’s lead author, Michele Bellesi, said.

‘We show for the first time that portions of synapses are literally eaten by astrocytes because of sleep loss.’

However, it was also discovered that microglial cells become more active after sleep deprivation. Previous studies have linked increased microglial activity with Alzheimer’s and other types of neutron degeneration. This could explain why sleep deprivation is correlated with a greater likelihood of developing dementia.

Instant analysis
The authors objectively demonstrate that chronic sleep deprivation is convincingly associated with the destruction of neural transmission components by astrocytes and microglial cells. Destructive activity by the latter cell type has been linked to the onset of Alzheimer’s and other neurodegenerative diseases.

While the scientific methodology employed is rigorous, the results suggest a complex associative relationship but they do not in themselves prove causality.
Research score: 3.5/5
JCH