REM Sleep Behavior Disorder (RBD) is a disorder that involves motor activity (violent twitching and muscle contractions) during sleep.

Unlike other motor sleep disorders such as sleepwalking, RBD movements occur during Rapid Eye Movement (REM) sleep. REM sleep is normally characterized by sleep paralysis. Research conducted at the University of Toronto found that the neurotransmitter Glycine, an amino acid, is responsible for suppressing muscle twitches in REM sleep. It has been discovered that a deficiency in glycine levels in brain cells that control muscles is to blame for the violent muscle contractions that mimic the primary symptom for RBD.

“This study shows the mechanism that suppresses muscle twitches in REM sleep, and this will lead to better treatments and potential cures for this disorder,” says John Peever, assistant professor at the university, and discoverer of the link. “Treating REM sleep disorder may have much broader implications, since within five to eight years of being diagnosed with this disorder, 60% to 80% of individuals eventually develop Parkinson’s disease.”

The findings were published in the March 26th edition of the Journal of Neuroscience.