Abstract
INTRODUCTION: Chronic pain is highly prevalent in US military Veterans. Non-opioid and non-pharmacologic treatments are recommended when clinically appropriate, but research on the mechanisms underlying benefits of these treatments is lacking. Here, we examined the role of sleep in the effects of three non-pharmacologic pain treatments in Veterans. Specifically, we investigated whether treatment effects on sleep predicted treatment effects on pain occurring later, or vice versa. METHODS: Veterans enrolled in a randomized controlled trial were invited to participate in this supplementary sleep study. A total of 174 Veterans were randomized to one of three 8-session, in-person, group-based pain treatments: hypnosis, mindfulness meditation, or education control. Measurements included self-reported sleep disturbance, pain intensity, and pain catastrophizing; sleep duration was assessed with actigraphy. Sleep and pain measurements were obtained at baseline, posttreatment, and 3-month posttreatment follow-up. RESULTS: At baseline, average pain intensity was moderate (mean ± SD: 5.7 ± 1.7 on the 0-10 Numeric Rating Scale), pain catastrophizing was just below the clinically relevant threshold (mean ± SD: 28.6 ± 12.2 on the Pain Catastrophizing Scale), and subjective sleep disturbance exceeded the US population average (mean ± SD: 58.5 ± 8.1 on the Patient Reported Outcomes Measurement Information System Sleep Disturbance - Short Form). By contrast, objective sleep duration was consistent with the recommended daily sleep amount of 7-8 h for adults (mean ± SD: 8.3 ± 1.4 h). Across treatment conditions, pain intensity, pain catastrophizing, and subjective sleep disturbance were significantly less at posttreatment and 3-month follow-up than at baseline (p < 0.001). Actigraphic sleep duration did not differ significantly as a function of time. There was a high degree of covariation among the measures of pain intensity, pain catastrophizing, and sleep disturbance (p < 0.05). However, self-reported sleep disturbance was not significantly correlated with actigraphic sleep duration (|r| <= 0.13, p > 0.05). Sleep and pain variables observed at prior assessments predicted these same variables at subsequent assessments. There was no significant evidence that changes in pain preceded changes in sleep or that changes in sleep preceded changes in pain (all p > 0.05). DISCUSSION: For this study's Veterans, treatment-related changes in sleep and pain appeared to occur in parallel. The concomitant changes in sleep and pain suggest that therapies improving pain in Veterans may yield attendant benefits for the treatment of sleep, and possibly vice versa.