University of Montreal: Sleepwalking Is the Result of Poorly Regulated Deep Sleep

Sleepwalking is a non-rapid eye movement sleep (NREM) that affects up to 4% of adults. It can lead to serious injuries in sufferers and in some cases Sleepwalking leads to unintentional injury or harm to others. The next day can also be difficult because the sleepwalker will feel tired and sleepy. The causes of sleepwalking are not well known. In new research presented June 24 in the journal Frontiers in Neurology, Canadian researchers have promoted the hypothesis that sleepwalking is a waking disorder and the result of poorly regulated deep sleep.

Sleepwalking

The autonomic nervous system is abnormally activated

The scientists investigated how the autonomic nervous system, which regulates the body’s physiological functions and is measured through heart rate, affects deep sleep in sleepwalkers. They recruited 14 adults that sleepwalk. “One of the challenges of studying large groups of sleepwalkers is the relatively low prevalence of the disease in the adult population,” estimated Professor Antonio Zadra and Dr. Andrée-Ann Baril of the University of Montreal, the two lead authors of the study. Participants were evaluated with video polysomnography during one night and during recovery sleep, after 25 hours of sleep deprivation.

The researchers noted that sleepwalkers exhibit different autonomic nervous system responses. The responses of the sympathetic and parasympathetic nervous systems are abnormally activated. The former, which controls the activity of visceral organs and automatic body functions such as breathing and heart rate, is activated normally in a fight-or-flight situation. During sleep, the parasympathetic system is activated to maintain the body’s basic activities and allows for the storage of energy. In sleepwalkers, this is reversed and the sympathetic part is activated when the response of the parasympathetic system is weaker.

The parasympathetic system is suspected

“Although the causes of sleepwalking remain unclear, we know that sleepwalkers may experience abnormal interactions between wakefulness and deep sleep-related processes during sleep, even outside of their episodes,” the study authors noted. In other words, sleepwalkers may show evidence of both wakefulness and deep sleep; a state from which episodes of sleepwalking may occur. Our results indicate that compared to healthy adults, the autonomic nervous system of sleepwalkers enhances their parasympathetic activity during sleep. This opens a new and broader avenue for understanding the biological processes involved in sleepwalking.