It's the first evidence of this link -- and may point to a drug remedy for common sleep problems like sleep apnea, reports lead researcher Sid Gilman, MD, a neurologist with the University of Michigan at Ann Arbor, in a news release.
It also provides clues to neurological disorders like Parkinson's disease, because similar brain chemical patterns have been found in people with Parkinson's disease, says Gilman. Sleep disorders may be an early symptom in many cases of Parkinson's disease, he adds.
His studies appear in the current issue of the journal Neurology.
Studies in Sleep Lab
In his reports, Gilman details research involving 13 patients -- all with a brain disorder called multiple system atrophy, a complex, rare, and disabling disease that also involves serious sleep disturbances.
All the patients had sleep apnea, a disorder in which breathing stops during sleep. They also yelled and thrashed violently during the rapid eye movement (REM) phase of sleep -- what's known as REM sleep behavior disorder.
While multiple system atrophy is a rare disease, the studies' findings provide insight into the more common sleep problems that disrupt the lives of many people, says Gilman.
All the patients in his studies spent two nights in a sleep laboratory, hooked up with electrodes, sensors, and monitors that measured body changes throughout both nights. Changes in breathing, body movements, snoring, airflow through nose and mouth, and brain activity were recorded -- and the corresponding sleep stages were tracked.
Brain Changes = Sleep Problems
When researchers compared the 13 patients' results with 27 healthy people, they found very different patterns.
The 13 sleep-problem patients had far fewer brain cells -- neurons -- that produce the chemicals dopamine and acetylcholine. And those with fewer such neurons had the worst sleep problems.
Patients who had the lowest dopamine levels talked and thrashed while they slept. Those with the lowest acetylcholine-producing neurons had the most interruptions in their breathing during sleep.
Drug Treatment for Sleep Apnea?
The findings also contain clues to the link between brain chemistry and specific muscles involved in sleep apnea and other sleep disorders, Gilman says. For example, acetylcholine-producing neurons are connected to the part of the brain that controls muscles of the upper airway and tongue -- and are involved in sleep apnea.
It's evidence that some sleep problems -- like sleep apnea -- may be successfully treated with medications that replace dopamine, the news release states.