0280 Effect of Daily Transcutaneous Vagal Nerve Stimulation on Objective and Subjective Sleep Features in Healthy Adults

Abstract Introduction One key pathway through which the autonomic nervous system modulates sleep is via the vagus nerve. No study to date has examined the impact of daily vagal modulation on nightly sleep activity. Here, in a two-week, within-subject sham-controlled and counterbalanced study, we investigated the impact of daily, non-invasive vagal nerve stimulation on subjective and objective sleep features. Methods The Institutional Review Board of the University of Kentucky approved experimental procedures. Twenty healthy adults, aged between 18-65, were given ambulatory vagal nerve stimulators to wear at home for one week of active and one week of sham stimulation. Stimulation conditions were counterbalanced across participants. The device was worn for 15 minutes between 9 PM-11 PM each day before bedtime. Before and after sleep, participants completed the Karolinska Sleepiness Scale (KSS) to measure subjective sleepiness and completed daily diaries to gather subjective sleep outcomes. Participants also wore wrist actigraphs to objectively characterize behavioral sleep/wake patterns. Linear mixed effect models assessed the effect of tVNS on subjective and objective measures of sleep. Results tVNS had a significant impact on actigraphy indices of sleep behavior. Compared to sham stimulation nights, there was a significant reduction in wake after sleep onset (b=-17.12, p=.004), a significant improvement in amount of time spent asleep during the night (b=2.87, p=.01) and higher sleep efficiencies (b = 2.05, p=.01) on stimulation nights. No significant differences were found in KSS ratings before and after sleep or in subjective sleep assessments measured with daily diaries. Conclusion The results suggest that the use of daily tVNS may improve behavioral indices of sleep, highlighting the important role that autonomic activity may play in regulating nighttime sleep/wake function. Future studies should examine tVNS impacts on polysomnographically-measured sleep Support (if any)