Brain chemistry and different sleep disorders appear linked, according to 2 studies published in Neurology (July 8, 2004). The studies looked at the same 13 individuals with multiple system atrophy (MSA), a fatal, degenerative neurological disorder that is almost always accompanied by sleep disorders. All the MSA patients in the study also had obstructive sleep apnea and rapid eye movement (REM) behavior disorder. The purpose of the study was to explore the links between these sleeping disorders and the neurotransmitters dopamine and acetylcholine.
The 13 participants, along with 27 healthy control participants, slept in a clinical research center for 2 nights, hooked up to machinery that measured neurotransmitter levels, brain waves, eye movements, and more.
The focus of the first study was to determine if dopamine was related to REM sleep behavior disorder. "We found a very tight correlation [between the severity of REM sleep behavior disorder and the level of decrease in dopamine], so this suggests that there's a causal effect," said Sid Gilman, MD, FRCP, chairman of the department of neurology at the University of Michigan School of Medicine.
The second study looked to see if there was a relationship between the severity of obstructive sleep apnea and the degree of decrease of acetylcholine. "Here again, we found a good correlation. It's not allowing us to conclude but it's certainly suggesting that there might be a causative relationship between obstructive sleep apnea and this neurotransmitter," said Dr. Gilman.