A Boxing Match in the Sack?

REM sleep behavior disorder risk factors include smoking and pesticide exposure

(RxWiki News) A little unconscious kick or punch from a partner during sleep isn't too bad, but if nighttime feels like a boxing match, a rare and serious sleep disorder may be to blame.

A person with REM sleep behavior disorder acts out his or her dreams and is at a higher risk for developing Parkinson's and dementia. A recent study identified a range of environmental factors that increase a person's risk of developing the sleep disorder.

"See a sleep doctor if you punch or kick excessively in your sleep."

Ronald Postuma, MD, MSc, at the Research Institute of the McGill University Health Center in Montreal, led over two dozen colleagues to study patients recruited from 13 different sleep study centers specializing in the disorder.

The researchers surveyed 347 patients with REM sleep behavior disorder and 347 people of similar ages and genders who did not have the disorder for a comparison group. In the comparison group, 218 had other different sleep disorders, and 129 had no sleeping disorder at all.

The average age of the participants was about 68 years old, and the majority (81 percent) were male.

The risk factors for the sleep disorder that were significant enough to go beyond coincidence included smoking, past head injury, exposure to pesticides and an occupation as a farmer.

Patients with REM sleep behavior disorder were about 1.4 times more likely to be smokers, with 64 percent of the patients with the disorder classified as smokers compared to 56 percent of those without the disorder. No similar pattern emerged for caffeine or alcohol use.

Those with the disorder were 1.6 times more likely to have sustained a head injury, with 19 percent of the patients having the disorder compared to 13 percent without. Those with the disorder tended to have about a year a half less of formal schooling.

About 20 percent of those with the disorder had worked as farmers, compared to only 13 percent of those without it. Similarly, those who had been exposed to pesticides at their jobs were just over twice as likely to have the sleeping disorder.

"Because it is a rare disorder, it was difficult to gather information about enough patients for a full study," Dr. Postuma said. "Until now, we didn't know much about the risk factors for this disorder, except that it was more common in men and in older people."

Although rare, the disorder is serious because over half of those diagnosed with it develop a neurodegenerative disorder such as Parkinson's disease or dementia later in life.

William Kohler, MD, the director of the Florida Sleep Institute in Spring Hill, Florida, said he has seen a number of cases of this disorder, and the list of risk factors found in this study is not surprising given that the disorder's movement symptoms are caused by a lack of muscle tone during REM (rapid eye movement) sleep.

"Anything that can contribute to a change in the nerve pattern of control for muscle tone can do that," Dr. Kohler said. "Different chemical changes, such as medications like Prozac, have been noted to do that, so it's not unreasonable that these other indications they found could also do that."

Dr. Kohler said the most common treatment for the disorder is Klonopin (clonazepam), a medication in the class of benzodiazepines. Other patients may use Xanax (alprazolam) or melatonin.

"Melatonin in high doses of about 15mg has been effective, but classically, it's been clonazepam," Dr. Kohler said. " About 0.5 to 1 mg has 90 percent effectiveness in fixing it. It doesn't cure, but it controls the symptoms"

The study was published June 27 in the online issue of Neurology. The research was funded by the Fonds de Recherche du Québec – Santé. The authors declared no conflicts of interest.

Review Date: 
June 25, 2012