Research technique could aid diagnosis of sleepwalking while the subject is awake
Breakthrough research using virtual reality has revealed significant differences in how the brains of sleepwalkers and non-sleepwalkers control and perceive body movement.
The study, published in Current Biology, was carried out by researchers from the University of Central Lancashire (UCLan) and the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland.
Researchers used full body motion capture and virtual reality feedback to study the movement of sleepwalkers and non-sleepwalkers while they were awake, and for the first time found that the sleepwalkers exhibited increased automation in their movements.
Both groups took part in a walking task in which they walked with an avatar, towards a visual target in a virtual environment, then repeated this while counting backwards in steps of seven. Their walking speed and accuracy of movement were then recorded and analysed.
It was found that non-sleepwalkers significantly slowed down when having to count backwards while walking, yet sleepwalkers maintained a similar walking velocity in both conditions, confirming a strong link between sleepwalking and automatic control of locomotion. Furthermore, sleepwalkers were more accurate at detecting changes in the virtual reality feedback when faced with the mental arithmetic task.
Our research offers novel insight into this common sleep disorder and provides a clear scientific link between action monitoring, consciousness, and sleepwalking.
Somnambulism, or sleepwalking, currently affects between 2-4% of adults and can cause movements ranging from small gestures, to complex actions such as walking and even behaviours like getting dressed, driving a car, or playing a musical instrument, – all while asleep. This new relationship between sleepwalking and automatic movement control could potentially be used to aid diagnosis of sleepwalking while the subject is awake, rather than requiring an overnight stay in a sleep laboratory.
Dr Oliver Kannape, lead author of the study and lecturer in cognitive neuroscience at UCLan, said: “Traditionally, little has been known about daytime markers of sleepwalking, mostly because of the difficulty in investigating this condition experimentally. Our research offers novel insight into this common sleep disorder and provides a clear scientific link between action monitoring, consciousness, and sleepwalking.
“Advances in virtual reality technology have made this research possible and enabled us to investigate awake sleepwalkers in an innovative way and focus on movement automation and awareness. We are already exploring other applications of the use of this type of technology to help us uncover more about such complex human behaviours – behaviours that cannot be investigated using a brain imaging approach.”
Professor Olaf Blanke, director of the Center for Neuroprosthetics and head of the Laboratory of Cognitive Neuroscience at EPFL, added: “We found that sleepwalkers continued to walk at the same speed, with the same precision as before and were more aware of their movements than non-sleepwalkers.
“The research is also a first in the field of action-monitoring, providing important biomarkers for sleepwalkers – while they are awake.”