Sleep heart rate predicts next-day pain medication use in posttraumatic stress disorder inpatients.

Introduction: Chronic pain and posttraumatic stress disorder (PTSD) are common in Veterans, commonly co-occurring, and are associated with pain medication use. Objectives: Our primary aim in this study was to explore the relationship between sleep heart rate (HR) and respiratory sinus arrhythmia (RSA) on next-day prescription pain medication use in Veterans with PTSD. Methods: Seventy-eight male US military Veterans attending an inpatient treatment program for service-related PTSD were observed over an average of 78 nights. Sleep HR and RSA were recorded using mattress actigraphy, and daily pain medication prescription was obtained from electronic health record. Results: Binary logistic mixed-effects regression models were used to test the associations between sleep HR and RSA on next-day pain medication prescription. These revealed that higher sleep HR was predictive of higher rates of next-day pain medication prescriptions; however, sleep RSA was not. An analysis disaggregating between- and within-persons effects associating sleep HR and next-day pain prescription found evidence of the former but not the latter. Conclusion: These results replicate and extend those of Dudarev et al. (2024) in demonstrating a positive relationship between sleep HR and next-day pain in a new population, Veterans with deployment-related PTSD. They support a role of autonomic arousal in subjective pain and medication-seeking and suggest that hyperarousal may mediate the excess vulnerability of persons with PTSD to pain medication use.