Association Between Chronotype and Chronic Neuropathic Pain Sensitivity: A Pilot Prospective, Observational, Single-Center, Cross-Sectional Study

Chronotype defines an organism's biological preference for timing of activity and sleep. Being a morning chronotype (i.e., tending to wake up early and go to bed earlier at night) is associated with protection against chronic musculoskeletal pain and headaches, but the relationship between chronotype and neuropathic pain sensitivity remains unclear. The aim of this pilot study was to explore the relationship among chronotype, neuropathic pain sensitivity, and pain interference in patients with chronic neuropathic pain disorders. This was a prospective, observational, single-center, cross-sectional study. Patients were recruited from pain management clinics. The Morningness-Eveningness Questionnaire (MEQ) was used to evaluate circadian typology. Linear mixed-effects models, principal component analysis, and principal component regression were used to determine the predictors of pain intensity and pain interference evaluated by the Numeric Rating Scale (NRS) and Patient-Reported Outcomes Measurement Information System Pain Interference (PROMIS-PI) scores, respectively. We analyzed 38 adults who had at least one documented chronic neuropathic pain diagnosis. Morning-chronotype patients reported higher NRS scores over time and lower PROMIS-PI t-scores than did intermediate chronotypes. MEQ, depression, risk of sleep apnea, sleep quality, and body mass index (BMI) were all significant independent predictors of average NRS scores and PROMIS-PI t-scores. The population was small and homogeneously white, with an average age of 57 years. However, this population was representative of our pain clinic. Morning chronotypes are more sensitive to chronic neuropathic pain, reporting higher pain scores than do intermediate chronotypes. However, in this study, morning chronotypes were more resistant to neuropathic pain interference, suggesting that they may experience less disturbance of their physical, mental, and social activities than intermediate chronotypes. Further, larger studies are needed.