The feasibility of ambulatory heart rate variability monitoring in non-suicidal self-injury

The polyvagal theory proposes that the autonomic nervous system influences affective systems and top-down emotional regulation. Vagal tone, as indexed by heart rate variability(HRV), is a measure of emotion regulation capacity. It is possible that non-suicidal self-injury(NSSI) occurs at times of low vagal tone and that NSSI may increase it. Little is known about the feasibility of collecting ambulatory HRV data in the context of NSSI. This prospective observational study examined the feasibility of ambulatory HRV monitoring during NSSI. Ten participants wore a chest-based heart rate monitor and used a diary app for 1 week. Baseline characteristics were collected. Heart rate monitoring duration, diary app entries, distress scores, and NSSI occurrences were recorded. Participant experience was assessed in a post-study questionnaire. At baseline, six had a history of NSSI, in two of whom it was current. Ten participants wore the monitor for an average of 137h. Nine participants successfully used the diary app, making an average of 14 entries over a week. Although no NSSI occurred during the study, the overall experience of participation was positive. It is feasible to monitor HRV and collect app-based distress scores for a week, including in those with NSSI history.