Sleep and circadian rhythm disturbances as risk and progression factors for multiple chronic overlapping pain conditions: a protocol for a longitudinal study.

Introduction: Chronic overlapping pain conditions (COPCs), such as chronic low back pain (cLBP) and fibromyalgia, frequently cooccur and incur substantial healthcare costs. However, to date, much focus has been placed on individual anatomically based chronic pain conditions, whereas little is known about the mechanisms underlying progression to multiple (more than 1) COPCs. This study aims to address the gap by investigating the role of common and modifiable risk factors, specifically sleep and circadian rhythm disturbances, in the development of multiple COPCs.

Methods: The study will enroll 300 participants with cLBP, including 200 with cLBP only and 100 with cLBP plus other COPCs (ie, fibromyalgia, temporomandibular disorders, irritable bowel syndrome, and chronic headaches) and follow them up for 12 months. Sleep and circadian rhythms will be assessed using wireless sleep electroencephalography, 24-hour evaluation of the rhythm of urinary 6-sulfatoxymelatonin, actigraphy, and sleep diaries. Pain amplification using quantitative sensory testing, psychological distress using validated self-report measures, and the number of pain sites using a pain body map will also be assessed.

Perspectives: This research aims to (1) comprehensively characterize sleep/circadian disturbances in individuals with single and multiple COPCs using multimodal in-home assessments; (2) examine the associations between sleep/circadian disturbances, changes in pain amplification, and psychological distress; and (3) investigate the relationship among these factors and the progression in the number of pain sites, a proxy for multiple COPCs. The findings will provide insights into the mechanisms leading to multiple COPCs, potentially informing treatment and prevention strategies for these complex conditions.