Although almost everyone talks about the dreams they have at night–what happened, what they could mean, and so on–nobody talks about what the body does while dreaming. Of course, we can’t watch ourselves in the moment, but studying the body’s behavior during dreams can help us to understand the brain. That’s exactly what a team of French scientists set out to do earlier this year, and their findings are incredible.
About 20% of our sleep cycle consists of rapid eye movement (REM) sleep, which is marked by random, intense movement of the eyes and low muscle tone; REM sleep is also when dreaming occurs. While our brains and eyes may be racing during REM sleep, our bodies actually enter a state of paralysis so that we don’t injure ourselves in an attempt to act out dreams. The irony of an active mind but a perfectly still body has caused some experts to call REM sleep paradoxical or desynchronized sleep.
However, for people with REM sleep behavior disorder (RBD), the body isn’t so peaceful during dreams. RBD prevents the body from slipping into paralysis while the mind dreams, so people with RBD physically react to dreams by talking, throwing punches, jumping out of bed, and so on, while remaining asleep. This can be dangerous for both themselves as well as the people around them.
Recently, researchers from the Lyon Neuroscience Research Center at the Université Claude Bernard Lyon 1 in Lyon, France conducted a study to explore possible neural foundations of RBD. In a rat model, the researchers focused on a set of neurons known as the sublaterodorsal nucleus–which has long been considered the area of the brain responsible for REM sleep–and blocked the expression of a gene that controls secretion of glutamate, a key neurotransmitter in the central nervous system. By preventing glutamate expression, the scientists hoped to isolate the sublaterodorsal nucleus from the rest of the brain, thus making REM sleep impossible. Much to their surprise, however, even though the nucleus was not connected to the brain and the rats were not paralyzed, they still entered REM sleep. The rats’ state was similar to that of a person with RBD insofar as they were both experiencing REM sleep while unparalyzed.
Although the French scientists’ didn’t expect the eventual findings of the study, their findings are still significant. Since RBD is associated with diseases like Parkinson’s and narcolepsy, so this new information can provide leads for the future study and treatment of those conditions. Also, these discoveries leave the door wide open for future research on the relationship between our dreams, our bodies, and our eyes!