Understanding REM Sleep Paralysis

During REM sleep - the deep sleep where most recalled dreams occur - muscles that move the eyes and those involved in breathing continue to move, but most of the body's other muscles are stopped; probably to prevent injury. In a series of experiments, University of Toronto neuroscientists Patricia Brooks and John Peever reported in the July 2012 edition of Journal of Neuroscience that the neurotransmitters gamma-aminobutyric acid (GABA) and glycine caused REM sleep paralysis in rats by "switching off" the specialized cells in the brain that allow muscles to be active. This finding reversed earlier beliefs that glycine was the only inhibitor.

Identifying the neurotransmitters and receptors involved in sleep-related paralysis, points researchers to possible targets for developing treatments for sleep-related motor disorders such as Restless Legs Syndrome, teeth grinding and of course sleep paralysis.

Previous research suggested neurotransmitter receptors called ionotropic GABA A/glycine receptors in the motor neurons caused REM sleep paralysis. However, when the researchers blocked these receptors, REM sleep paralysis still occurred. The researchers found that to prevent REM sleep paralysis, they had to block GABA A, GABA B and glycine receptors. In other words, only when the motor cells were cut off from every source of GABA and glycine, the paralysis did not occur, allowing the rats to exhibit high levels of muscle activity when their muscles should have been inactive. The data suggest the two neurotransmitters must both be present together to maintain motor control during sleep, rather than working separately.

The finding could be especially helpful for those with REM sleep disorder as well as those who suffer from sleep paralysis as a side effect of narcolepsy. This is an interesting study with significant “real world” applications but it will take at least a decade of additional work on animals and humans before we might see a form of medication that blocks the receptors for GABA A, GABA B and glycine available to use.

 John Cherry

(Added to website 24th July 2012)