[LUM#20] Restless Nights
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 laboratory, explains Euromov1 laboratory and a neurologist at the sleep center at the Beau Soleil Clinic.
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. So why do we sometimes feel like 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 cycle consists of different stages that follow one another; cycles repeat throughout the night and are often interspersed with micro-awakenings—which are unconscious because they’re too brief—or longer awakenings that we can 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 more prevalent toward the end of the night. “It corresponds to a period during which brain activity is similar to that of the waking phase; 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 peaceful, uninterrupted sleep: they move around and exhibit abnormal motor behaviors—a condition known as parasomnia. 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 and tend to disappear in adults, ” explains the specialist.
But parasomnias can also occur during REM sleep, “in which case we refer to REM sleep behavior disorder,” the researcher notes . “Normally, a mechanism in the brainstem triggers muscle atonia that prevents movement—we’re effectively paralyzed—but in these patients, that mechanism malfunctions.” 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 his wife complains that he’s violent toward her while he’s asleep.” Sleepers who kick, 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 defends her by attacking their assailant, whereas in reality, it is she who is being struck.”
Parkinson's disease
These stories might be amusing if they weren’t indicative of more serious neurological disorders. “Eighty percent of patients with 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 has the unique property of aggregating, which leads to deposits known as Lewy bodies, ” explains the neurologist. By analyzing the brains of deceased patients with this disease, scientists have discovered that these 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 panic; these nighttime disturbances can also be a sign of sleep apnea, which primarily affects snorers and overweight patients. But in any case, it’s always important to get an early diagnosis for better management.” If a diagnosis of REM sleep behavior disorder is made, patients will be closely monitored to better identify the potential onset of Parkinson’s disease—and perhaps prevent its onset. “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 sleeping, or if you sometimes hurt yourself at night by kicking the wall or falling out of bed, it’s important to seek medical advice, ” insists Valérie Cochen de Cock.
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- Euromov (UM, IMT Mines Ales)
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