Parasomnia: What Happens in the Brain During Sleepwalking?

Summary: Researchers have made significant progress in understanding parasomnias, complex sleep behaviors in which individuals are semi-conscious and often interact with their environment. The team explored brain activity during these episodes, revealing that dreams and unconscious actions can occur during non-REM sleep, challenging previous assumptions about sleep stages and dream onset.

By inducing parasomnia in controlled laboratories and monitoring brain activity with sophisticated equipment, the study discovered varying brain patterns based on patients’ experiences during the episodes. This research not only provides insight into the neurological basis of parasomnias, but also opens the door to more effective treatments.


  1. The study found that 56% of parasomnia episodes involved dreams, often with themes of danger or doom.
  2. Patients were generally unaware of the external stimuli (such as loud sounds) that triggered their episodes, indicating a profound disconnection from their immediate environment.
  3. The research could lead to targeted treatments for parasomnias, moving away from general sleeping pills and toward interventions targeting specific neural activities.

Source: KNOW

Researchers from the Netherlands Institute of Neuroscience have taken a first step by exploring a rather complex question: what happens in the brain of a person who can be considered “stuck” between sleep and wakefulness ?

Most of us imagine a sleepwalker as someone who walks around unconsciously with their eyes closed and arms outstretched in front of them. In reality, sleepwalkers usually have their eyes open and can have complex interactions with their environment.

Sleep scientists refer to these abnormal sleep behaviors as “parasomnia,” which can include simple behaviors like sitting up in bed and appearing confused, but also more elaborate behaviors like getting out of bed and moving around or screaming with an expression. fearful facial expression.

Although parasomnias of this type are more common in children, approximately 2 to 3% of adults still experience them regularly. Parasomnias can be distressing for both the sleeper and their partner.

“Those affected may hurt themselves or others during the episodes and may later feel deeply embarrassed for what they have done,” explains Francesca Siclari, head of the Dreams laboratory.

Parasomnia episodes in the laboratory

Siclari and his team conducted this study to better understand what happens in the brain during parasomnias.

“It was generally believed that dreams only occurred during one stage of sleep: REM sleep. We now know that dreams can also come true in other phases. Those who experience parasomnias during non-REM sleep sometimes report having dreamlike experiences and sometimes appear completely unconscious (i.e., on autopilot).”

To understand what explains these differences in experience, Siclari and his team studied the experiences and brain activity patterns of parasomnia patients in non-REM sleep.

Measuring a person’s brain activity during an episode of parasomnia is no easy task. The patient must fall asleep, experience an episode and record their brain activity as they move around.

“There are currently very few studies that have successfully overcome this problem. But thanks to the many electrodes we use in the laboratory and some specific analysis techniques, we can now obtain a very clear signal, even when patients are moving,” explains Siclari.

Siclari’s team can induce a parasomnia episode in the lab, but it requires two consecutive recordings. During the first recording, the patient is sleeping normally. This is followed by a night during which the patient is kept awake and is not allowed to sleep until the next morning.

During this recording, the patient is exposed to a loud sound as they enter the deep sleep phase. In some cases, this results in an episode of parasomnia. After the episode, the patient is asked what came to mind.

The brain during an episode of parasomnia

In 56% of episodes, patients reported dreaming during the episode.

“It was often about misfortune or imminent danger. Some said they thought the ceiling was going to collapse.

“One patient thought he had lost his baby and was looking in the sheets and got up in bed to try to stop the ladybugs from sliding down the wall and dying,” Siclari says.

“In 19% of cases, patients felt nothing and simply woke up to find themselves doing things, almost as if in a trance.” Another small portion said they experienced something but couldn’t remember what it was.

Based on these three categories, Siclari’s group compared the measured brain activities and found clear parallels.

“Compared to patients who experienced nothing, patients who dreamed during the episode showed activations similar to the brain activations previously found for dreaming, both immediately before the episode and also during the episode. “

Siclari: “What determines whether the patient will be completely unconscious or dreaming seems to depend on the state the patient is in at the time.

“If we activate the brain while they are probably already dreaming, they seem to be able to ‘do something’ from the activation, whereas when their brain is largely ‘inactivated’, simple behaviors seem occur without experience.

» Interestingly, patients almost never mention the sound that triggered the parasomnia episode, but rather some other type of imminent danger. The more we increase the volume, the more likely we are to cause an episode.

The next steps

As this is only the first step, there is plenty of room for follow-up studies.

“Ideally, we would like to set up a system that allows more people to record their sleep at home, where they may also have much more complex and frequent episodes.

“We would also like to repeat the same type of studies on people with parasomnias during REM sleep. By measuring brain activity as in this study, we hope to ultimately better understand which neural systems are involved in different types of parasomnias.”

Although there is still much research to be done, Siclari is confident that her work can provide valuable insights.

“These experiences are very real for patients and most already feel relieved to share them with us. Like previous studies, our research clarifies what they experience, which is educationally valuable. Additionally, our work could contribute to more specific drug interventions in the future.

“Parasomnias are often treated with nonspecific sleeping pills, which are not always effective and can have negative side effects. If we can deduce which neural system is functioning abnormally, we can eventually try to develop more specific treatments.

About this research news on parasomnia and consciousness

Author: Eline Feenstra
Source: KNOW
Contact: Eline Feenstra – KNAW
Picture: Image is credited to Neuroscience News

Original research: Free access.
“Shared EEG correlates between non-REM parasomnia experiences and dreams” by Francesca Siclari et al. Natural communications


Shared EEG correlates between non-paradoxical parasomnia experiences and dreams

Sleepwalking and associated parasomnias result from incomplete awakenings resulting from non-rapid eye movement sleep. Behavioral episodes may occur without awareness or memory, or in relation to dream experiences.

To understand what explains these differences in consciousness and memory, here we recorded episodes of parasomnia using high-density electroencephalography (EEG) and interviewed participants immediately afterwards about their experiences.

Compared to reports of no experience (19%), reports of conscious experience (56%) were preceded by high-amplitude EEG slow waves in anterior cortical regions and activation of posterior cortical regions, similar to the EEG correlates of dreaming described previously.

Recall of the content of the experience (56%), compared to no recollection (25%), was associated with higher EEG activation in the right medial temporal region before movement onset.

Our work suggests that EEG correlates of parasomnia experiences are similar to those reported for dreams and thus may reflect fundamental physiological processes involved in sleep awareness.

News Source :
Gn Health

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