Acoustic Stimulation to Study and Modulate Sleepwalking and Related Arousal Disorders

Overview

Disorders of Arousal (DoA)-such as sleepwalking, sleep terrors, and confusional arousals-are common sleep problems that happen during deep, non-dreaming sleep. Researchers do not fully understand what triggers these episodes or how to influence them. This study tests whether playing soft sounds during sleep can help researchers learn more about, and possibly induce or modulate, these episodes under safe, supervised conditions. Participants with DoA will spend two nights in the sleep laboratory, with painless sensors placed on the scalp and body (similar to a regular sleep study). On one night, no sound is played. On the other night, soft sounds are played during deep sleep. The order of the two nights is decided randomly for each participant. A small group of healthy volunteers without DoA will also take part, undergoing a single night with sound stimulation, to help researchers understand whether the sounds affect everyone the same way or specifically trigger episodes in people with DoA. A subgroup of participants with DoA will also take part in a later, exploratory step in which the sound is triggered automatically, in real time, based on brain activity patterns. The sounds used are very quiet, similar in volume to normal conversation, and stimulation is stopped right away if a participant shows any discomfort. The goal of this research is to better understand what triggers Disorders of Arousal, and to test whether sound-based stimulation could one day help study or manage this condition.

Disorders of Arousal (DoA)-including sleepwalking, sleep terrors, and confusional arousals-are NREM parasomnias whose underlying neurophysiological triggers remain poorly understood. A growing body of evidence suggests that DoA episodes do not emerge randomly from sleep but arise from identifiable pre-episode EEG states characterized by increased slow-wave activity and reduced cortical activation, consistent with a transient state of arousal instability. Closed-loop acoustic stimulation (CLAS) is an established, non-invasive method for probing and modulating NREM sleep physiology, but has not previously been applied in the specific context of NREM parasomnias. This study investigates whether controlled acoustic stimulation, initially delivered with randomized timing and subsequently in a real-time, EEG-triggered closed-loop fashion, can reliably elicit or modulate DoA episodes under supervised laboratory conditions. A small group of healthy volunteers undergoes a single stimulation night to estimate the specificity of stimulation-elicited motor responses, helping distinguish genuine DoA vulnerability from a non-specific arousal response to sound. The within-subject, randomized-order design in DoA participants allows each to serve as their own control, isolating the effect of acoustic stimulation from other sources of night-to-night variability. The exploratory closed-loop sub-study tests the technical feasibility of triggering stimulation based on real-time EEG markers of vulnerability, representing a first step toward future predictive or modulation-based approaches for this condition. This study is part of a broader research programme on the neurobiological characterization of Disorders of Arousal; related observational components (including neuroimaging, neuropsychological assessment, and home monitoring) are registered separately.