[LUM#20] Eventful Nights

[LUM Magazine, Podcast] - Published on October 31, 2023 in Science and Society

In some cases, nighttime movements can be an early sign of Parkinson’s disease, which may develop years later. When should you be concerned, and who should you consult? Valérie Cochen de Cock, a researcher at the Euromov¹ and a neurologist at the sleep center at the Beau Soleil Clinic.

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While our days can sometimes be hectic, our sleep is supposed to be still. “When we sleep, we normally don’t move,” explains Valérie Cochen de Cock, a researcher at the Euromov laboratory. Why, then, do we sometimes feel as though we’re moving while we sleep? “In reality, these movements usually occur during the micro-awakenings that punctuate sleep, ” the neurologist explains. For while sleep may seem uniform, it actually has many facets. “A sleep cycle consists of different stages that follow one another; these cycles repeat throughout the night and are often interspersed with micro-awakenings—which we’re unaware of because they’re too brief—or longer awakenings that we may remember.” There are two main stages: slow-wave sleep, which starts out light and then becomes deep and predominates early in the night, and REM sleep, which is most prevalent toward the end of the night. “It corresponds to a period during which brain activity is similar to that of the waking state; this is when we dream, ” explains Dr. Cochen De Cock, who sees patients in a unit specializing in the treatment of sleep disorders at the Beau Soleil Clinic.

Parasomnias

And for some people, nights are not a long, peaceful river: they move around and exhibit abnormal motor behaviors—a condition known as parasomnias. Some of these disturbances occur during deep slow-wave sleep. There are three types of disorders: sleepwalking, confusional arousals, and night terrors. “These are fairly common in children but tend to disappear in adults, ” explains the specialist.

But parasomnias can also occur during REM sleep phases; “this is referred to as a REM sleep behavior disorder,” the researcher points out . “Normally, a locking mechanism in the brainstem triggers muscle atonia that prevents movement—we’re essentially paralyzed—but in these patients, this mechanism malfunctions.” It’s a disorder that takes a surprising form, to say the least. “Our typical patient is a man over 50 who comes in for a consultation saying that his wife complains he’s violent toward her while he’s asleep.” These sleepers hit, scream, and may even go so far as to try to strangle their bed partner. “When we interview the person, we find a dream narrative that explains the behavior: the sleeper dreams that his partner is being attacked and that he is defending her by attacking their assailant, when in reality it is she who is being struck.”

Parkinson's Disease

These stories might raise a smile if they weren’t indicative of more serious neurological disorders. “80% of patients with a REM sleep behavior disorder will develop Parkinson’s disease within the next 10 years, ” explains Valérie Cochen de Cock.

Why does this sleep disorder precede the onset of the first symptoms of this neurological disease? “In Parkinson’s disease, a protein called alpha-synuclein tends to aggregate, leading to deposits known as Lewy bodies, ” explains the neurologist. By analyzing the brains of deceased patients with this disease, scientists have found that the deposits form gradually and progress upward from the brainstem, which is located in the lower part of the brain. “This is precisely the region responsible for muscle atonia during sleep—our so-called ‘safety lock.’ That is why movements during REM sleep are a sign that precedes the clinical onset of the disease by several years.”

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The neurologist urges sleepers who recognize these symptoms to seek consultation at a specialized clinic. “There’s no need to be alarmed; these nighttime disturbances can also be a sign of sleep apnea, which primarily affects patients who snore and are overweight. But in any case, it’s always important to get an early diagnosis for better management.” If a patient is diagnosed with a REM sleep behavior disorder, they will be closely monitored to better identify the possible onset of Parkinson’s disease—and perhaps prevent it from developing. “At this time, there is no preventive treatment; however, studies show that physical activity is effective in slowing the onset of the disease.”

The specialist, who is part of a group of about 100 researchers studying rapid eye movement (REM) sleep behavior disorder, is participating in a major national study aimed at characterizing sleep disorders in Parkinson’s disease, which will begin in September 2023. “If your partner complains about violent movements while you’re asleep, or if you sometimes hurt yourself at night by hitting the wall or falling out of bed, it’s important to seek medical advice, ” insists Valérie Cochen de Cock.