Sleep Experts Awaken Interest in Parasomnias

It’s amazing what some people do while they’re asleep, sleep-disorder experts say.

They talk, scream, gesticulate, attempt to have sex, leap out of bed, raid the refrigerator, drive cars, and even attempt to kill their spouses. The official name for such abnormal behaviors is “parasomnias” (see "How Parasomnias Can Be Manifest" below).

Although traditionally scientists paid little heed to parasomnias, they have taken more interest in them during the past quarter-century and have learned some valuable things about them, especially during the last 10 years.

“One of those things is that sleep and wakefulness can coexist,” Karl Doghramji, M.D., a professor of psychiatry at Thomas Jefferson University and medical director of the Jefferson Sleep Disorders Center, said in an interview. “Another is the understanding that different sleep states have different types of mentation. We used to think that during REM sleep, people have dreams, cognitive experiences, and emotional experiences, but that in non-REM sleep, people have sort of a blank mind. We now know that in certain non-REM parasomnias, such as sleepwalking and sleep talking, people engage in complex behaviors that are seemingly very purposeful or goal directed.”

These discoveries, he pointed out, “tie in very nicely with the concept of the unconscious that Freud and many others championed many years ago.”

It is also now known that the non-REM parasomnias, such as sleepwalking and sleep talking, tend to run in families, Dimitri Markov, M.D., an assistant professor of psychiatry at Thomas Jefferson University and a sleep specialist, said during an interview. “So people who have [these behaviors] in the family are apt to think that they are normal.” Moreover, sleep deprivation and sleep apnea can trigger sleepwalking, at least in those genetically predisposed to it, he noted.

Sleepwalking is likewise more common than previously thought, Maurice Ohayon, M.D., D.Sc., Ph.D., a professor of psychiatry at Stanford University and a sleep specialist, and his colleagues reported in the May 15 Neurology. They used a large, representative sample of the U.S. population for their study and found that 3.6 percent of the sample reported at least one episode of sleepwalking in the previous year. “This 3.6 percent represents 8.5 million Americans,” he told Psychiatric News. “That is considerable…. Narcolepsy [by contrast affects] 0.04 percent of the population.”

For Carlos Schenck, M.D., a professor of psychiatry at the University of Minnesota, September 11, 1982, was special for several reasons. He not only started his sleep-medicine career on that day, but also encountered an unusual case. It was a 67-year-old man who had charged out of bed thinking he was a football player and who had crashed into his dresser. This led to Schenck and his colleagues discovering a parasomnia that hadn’t been known before. They named it “REM sleep behavior disorder.”

“And then we discovered more men, particularly middle-aged and older men, acting out these violent dreams.” Schenck said during an interview. “These men were all pleasant individuals, married for decades before they developed this disorder. Their wives could attest to the fact that there was no tendency for irritability or anger or anything like that. They would have noticed it after being married for 20, 30, or 40 years.”

“Today, probably more is known about REM sleep behavior disorder than all the other parasomnias,” John Winkelman, M.D., an associate professor of psychiatry at Harvard Medical School and a sleep specialist, told Psychiatric News.

For instance, the disorder afflicts mostly elderly men and may precede Parkinson’s disease or Lewy body dementia by five, 10, or 15 years, Markov reported, although sometimes the Parkinson’s disease or dementia may manifest itself first and then the REM sleep behavior disorder follows. Although not all older men who have the disorder will develop Parkinson’s or dementia, “the numbers could be as high as 50 percent,” Markov said.

“Some preliminary epidemiological studies indicate that 0.5 percent of men have the disorder,” Schenck added. “However, most of us in the field really believe that in men in the older age groups” the prevalence could range from 1 percent to 5 percent.

And then in 1991, Schenck and his colleagues identified sleep-related eating disorder, which is a non-REM parasomnia, and in 1997 wrote a major review article about another non-REM parasomnia that others had identified. It was sexsomnia—abnormal sexual behavior during sleep. Today, scientists know that sexsomnia sometimes occurs in people with a history of sleepwalking and of sleep terrors, said Schenck. But they also believe that sleep apnea can trigger it.

Still, a lot more needs to be learned about parasomnias, experts concur.

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For example, several studies have suggested that an antihypertensive medication can reduce the frequency and intensity of nightmares in veterans with posttraumatic stress disorder, Winkelman stated, but “we don’t have good insights into the biology of nightmares.” The same holds regarding the biology of sleepwalking, night terrors, sleep-related eating disorder, and other parasomnias, he said.

“We know that psychiatric medications can trigger REM sleep behavior disorder,” said Schenck. “We know that sleeping pills can trigger sleep-related eating. But basically we need to know the whole range of conditions that can predispose people to a variety of parasomnias.”

So what new knowledge about parasomnias might be emerging during the next decade or so?

“We are coming a bit closer, I think, to identifying some of the genetic predispositions of non-REM parasomnias,” said Doghramji. “Work is being done with some of the folks who have these disorders to understand familial tendencies and genetic predispostions. In the next decade, I hope that we’ll also be able to identify which subpopulation of REM sleep behavior disorder patients goes on to develop Parkinson’s disease or other neurodegenerative brain disorders. And hopefully we will be able to predict which patients with the disorder should receive treatment prophylactically with dopa-mine medications or other medications before the problem becomes full-blown” (see "Parasomnias Rarely Related to Psychiatric Illness" below).

“I think we will learn more about the abnormal brain physiology triggering the parasomnias,” Schenck predicted. And one reason why, he explained, is that high-density EEG machines are now becoming available. For example, “at the University of Wisconsin, Madison, they are using 156-electrode EEGs—that is an enormous amount. Ordinarily we use only four electrodes. To study parasomnias in a sleep lab, it could be eight to 12. But to have 156 electrodes, you can really go deep into the brain … to discover the origins of parasomnias.”