Melatonin’s key role in REM sleep revealed

A major breakthrough in understanding the mechanism of sleep offers new opportunities for treating sleep disorders and related neuropsychiatric disorders: scientists have identified the melatonin receptor MT1 as a key regulator of rapid eye movement (REM) sleep.

REM sleep is crucial for dreaming, memory consolidation, and emotional regulation. In the brain, the melatonin MT1 receptor influences a type of neuron that synthesizes the neurotransmitter and hormone norepinephrine, found in an area known as the Locus Coeruleus, or “blue spot” in Latin.

During REM sleep, these neurons become quieter and stop their activity. Serious diseases such as Parkinson’s disease and Lewy body dementia, for which there are currently no effective treatments, are associated with disruptions in REM sleep.

“This discovery not only advances our understanding of sleep mechanisms, but also has significant clinical potential,” said Gabriella Gobbi, lead investigator of a new study published in the Journal of NeuroscienceShe is a professor of psychiatry at McGill University, a clinical scientist at the McGill University Health Centre, and the Canada Research Chair in Therapeutics for Mental Health.

The science of snoozing

Human sleep occurs in a precise sequence of non-REM and REM phases, each of which has a distinct physiological function. REM sleep plays a crucial role in memory consolidation and emotional regulation. Non-REM sleep supports physical recovery and repair processes. Disruptions to this cycle can impair cognitive function and increase vulnerability to neuropsychiatric diseases.

Until now, the specific receptor that triggers REM sleep has eluded scientists. The new study has identified the melatonin MT1 receptor as a key regulator of this sleep phase. Using a new drug that targets MT1 receptors, researchers have successfully increased the duration of REM sleep in laboratory animals while simultaneously reducing neuronal activity.

“Currently, there are no medications that specifically target REM sleep. Most hypnotic medications on the market, although they increase total sleep time, tend to negatively affect REM sleep,” said Dr. Stefano Comai, co-senior author of the study and professor at the University of Padua and associate professor at McGill University.

Further research into the neurobiology and pharmacology of REM sleep is crucial to developing targeted treatments that can improve the quality of life of patients afflicted with these debilitating diseases, the researchers said. As scientists continue to explore the complexities of sleep regulation, the hope for effective interventions in neurological disorders becomes increasingly promising.