Association between autophagy and rapid eye movement sleep loss-associated neurodegenerative and patho-physio-behavioral changes.

Rapid eye movement (REM) sleep is a unique physiological process at least expressed in mammals. Its disturbance affects many psycho-somato-physiological processes including cardio-vascular-respiratory systems, brain excitability, neurogenesis, synaptic pruning, and memory consolidation. While it is altered in most neurodegenerative disorders including Alzheimer's disease (AD), Parkinson's disease (PD) and REM sleep behavior disorder (RBD), the detailed mechanism of inducing such action is unknown. Independent studies have reported that by clearing unwanted, dysfunctional intracellular debris, wastes, etc., autophagy maintains cellular health, integrity, and homeostasis. Abnormality in autophagy causes neuronal dysfunction including death, leading to neurodegenerative disorders. It has also been reported that by modulating noradrenaline (NA) levels, REM sleep maintains neuronal integrity and house-keeping functions of the brain. Using PUBMED, we surveyed the literature and found isolated, independent studies showing that autophagy dysfunction is associated with acute and chronic neurodegenerative and patho-physio-behavioral changes, which are also associated with REM sleep loss. We collated these scattered findings, which strongly support our contention that elevated NA associated with REM sleep loss is likely to affect autophagy in neurons, disturbing neuronal integrity and homeostasis and leading to altered brain functions and associated disorders.