Scientists found that lack of sleep may increase risk of Alzheimer's disease and other neurological disorders. Researchers from Marche Polytechnic University in Italy compared the brains of two groups of mice. One group had been allowed to sleep for as long as they wanted or had been kept awake for eight hours. Another group were kept awake for five days in a row – mimicking the effects of chronic sleep loss.
The team looked at a type of glial cells called astrocytes which prune unnecessary synapses in the brain to remodel its wiring. Another type, called a microglial cell, prowls the brain for damaged cells and debris, researchers said. They found that after an undisturbed sleep, astrocytes appeared to be active in around six per cent of the synapses in the brains of the well-rested mice. However, astrocytes seemed to be more active in sleep-deprived mice – those that had lost eight hours of sleep showed astrocyte activity in around eight per cent of their synapses, while the cells were active in 13.5 per cent of the synapses of the chronically sleep-deprived animals, researchers said.
This suggests that sleep loss can trigger astrocytes to start breaking down more of the brain's connections and their debris, reported 'New Scientist'. "We show for the first time that portions of synapses are literally eaten by astrocytes because of sleep loss," said Michele Bellesi of the Marche Polytechnic University. "In the short term, this might be beneficial – clearing potentially harmful debris and rebuilding worn circuitry might protect healthy brain connections," said Bellesi. "But it may cause harm in the long term, and could explain why a chronic lack of sleep puts people at risk of Alzheimer's disease and other neurological disorders," he added.