Researchers have found sleep medications commonly used to treat insomnia, or difficulty falling and remaining asleep, to significantly reduce rapid eye movement (REM) sleep behaviour disorder.
The study findings suggested that these medications, known as dual orexin receptor antagonists, could also potentially cause fewer side effects.
REM sleep behaviour disorder is a condition, mostly affecting adults aged over 50, in which one often unknowingly physically acts out their dreams with vocal sounds or sudden, violent arm and leg movements during slumber, leading to significant injury to themselves or bed partners.
Outlining a model to better describe how REM sleep behaviour disorder develops due to neurodegeneration associated with tau protein accumulation, Mount Sinai researchers in the US in this study have provided an early-life biomarker of impending neurodegeneration.
This, they say, could guide future prevention and treatment.
Their study is published in the Journal of Neuroscience.
“We identify a novel model in which REM sleep behaviour disorder can develop, due to neurodegeneration associated with accumulation of tau protein, and a novel therapy that could minimize REM sleep behaviour disorder,” said corresponding author Andrew W. Varga, associate professor of Medicine (Pulmonary, Critical Care and Sleep Medicine) at the Icahn School of Medicine at Mount Sinai.
In a mouse model, the researchers examined the brain for neurodegenerative disorders following abnormal deposits of tau, a protein that normally helps stabilise the internal skeleton of nerve cells in the brain.
They analyzed behavioral states including wakefulness, phases of REM (sleep with dreams), phases of non-REM (sleep without dreams), length of sleep, transitions from waking to sleep, and how some factors are related to age.
The researchers found nearly a third of the older subjects exhibited dream enactment behaviours reminiscent of REM sleep behaviour disorder, including chewing and limb extension.
Administering a dual orexin receptor antagonist twice during a 24-hour period was found to not only reduce the time it took to fall asleep and increase both the quality and duration of sleep, but also reduce levels of dream enactment.
The medication was administered twice to evaluate sleep in light and dark phases.
“We anticipated finding breakdown of sleep quality with progressive neurodegeneration related to tau accumulation, but the observation of dream enactment was a surprise,” said lead author Korey Kam, assistant professor of Medicine (Pulmonary, Critical Care and Sleep Medicine) at Icahn Mount Sinai.
“It was even more surprising and exciting to observe that a dual orexin receptor antagonist could significantly minimize the dream enactment behaviours,” said Kam.