An ameliorative effect of recovery sleep on total sleep deprivation-induced neurodegeneration

Neurodegenerative changes following sleep deprivation (SD) result in debilitating behavioral and cognitive dysfunction. SD causes gradual cognitive impairment and later results in neurodegeneration. These changes are thought to be the consequences of cellular disorganization and degeneration in selected brain areas – the hippocampus, prefrontal cortex, amygdala, and hypothalamus. We investigated the histological changes in mice exposed to 6 days SD and to the effects of 2 days of recovery sleep in the brain regions listed above. Cytological changes, total viable cell count in hippocampal subregions, Bcl-2 expression, and degenerative changes like cell morphology and membrane integrity of neurons were evaluated. Results demonstrated that prolonged SD decreased the count of viable and healthy cells and caused a decrease in Bcl-2 positive cells and an increase in degenerated cells with pyknotic morphology, chromatolysis and darkly stained cytoplasm. Degenerative changes were ameliorated by 2 days of recovery sleep or rehabilitation after SD. Data suggest that chronic SD constitutes a severe threat to the brain and leads to neurodegeneration, while rehabilitation or recovery sleep ameliorates or protects the brain from neurodegenerative challenges.