[LUM#20] Restless Nights

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

In some cases, nocturnal movements can be a precursor to 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 neurologist at the sleep center at the Beau Soleil clinic.

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While our days may sometimes be eventful, our sleep is supposed to be motionless. "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 normally occur during the micro-awakenings that punctuate sleep, " explains the neurologist. Although 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 interrupted by micro-awakenings, which are unconscious because they are too brief, or by longer awakenings that we can remember." There are two main stages: slow-wave sleep, which is light at first and then deepens, predominating at the beginning of the night, and REM sleep, which predominates at the end of the night. "This corresponds to a period during which brain activity is similar to that of the waking phase, and it is at this time that 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

For some people, nights are not always peaceful: they move around and exhibit abnormal motor behavior, which is referred to as parasomnia. Some of these disturbances occur during deep slow-wave sleep. There are three types of disorders: sleepwalking, confusional arousal, and night terrors. "These manifestations are quite common in children and tend to disappear in adults, " says the specialist.

But parasomnias can also occur during REM sleep, "in which case we refer to it as REM sleep behavior disorder," the researcher points out . Normally, a locking mechanism in the brain stem causes muscle atony that prevents movement, leaving us 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 and says that his wife complains that he is violent towards her while he is asleep." These sleepers kick, scream, and may even go so far as to try to strangle their bed partner. "When we question the person, we find a dream story that explains the behavior: the sleeper dreams that his partner is being attacked and that he defends her by attacking their attacker, when in reality it is she who is being hit."

Parkinson's disease

These stories might raise a smile, were it not for the fact that they are precursors to more serious neurological disorders. "80% of patients who exhibit abnormal behavior during REM sleep 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 peculiarity of aggregating, which causes deposits called Lewy bodies, " replies the neurologist. By analyzing the brains of deceased patients with this disease, scientists have found that the deposits form gradually and progressively from the brain stem, which is located in the lower part of the brain. "This is precisely the region responsible for atonia during sleep, our famous sleep paralysis. This is why movements during REM sleep are a sign that precedes the clinical manifestation of the disease by a few years."

Consult

The neurologist advises sleepers who recognize themselves in this description to consult a specialist. "There is no need to be alarmed, as these nocturnal disorders can also be a symptom of sleep apnea, which mainly affects patients who snore and are overweight. But in all cases, it is always important to be able to make an early diagnosis for better treatment." If diagnosed with REM sleep behavior disorder, patients will be closely monitored to better identify the possible onset of Parkinson's disease. And perhaps prevent its onset. "At present, there is no preventive treatment, but studies show that physical activity is effective in slowing the onset of the disease."

The specialist, who is part of a group of around 100 researchers working on 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 of violent movements during your sleep, or if you injure yourself at night by kicking the wall or falling out of bed, it is important to seek medical advice, " insists Valérie Cochen de Cock.