Eveningness intensifies the association between musculoskeletal pain and health-related quality of life: a Northern Finland Birth Cohort Study 1966.

People with an evening (E)-type preference (ie, chronotype) experience musculoskeletal (MSK) pain and reduced health-related quality of life (HRQoL) more often than morning (M) types. Musculoskeletal pain is a well-established contributor to reduced HRQoL. This study aimed to evaluate whether eveningness amplifies the association between MSK pain and HRQoL in contrast to morningness. Questionnaire data on MSK pain dimensions (intensity, disability at work, number of pain sites [NPSs], and frequency), chronotype, covariates (sex, sufficiency of sleep duration, mental distress, and presence of coexisting diseases), and HRQoL (measured by 15D) were collected among 46-year-old individuals belonging to the Northern Finland Birth Cohort 1966 (N = 4257). Individuals without any MSK pain were excluded. General linear models were conducted to estimate the associations between chronotypes, MSK pain dimensions, and HRQoL. The interaction terms (chronotype × pain dimension) were tested in the models. There were 13% E-types and 43% M-types in the study sample. Each pain dimension and chronotype were related to HRQoL. In the sex-adjusted chronotype-specific models, the reduction in HRQoL in relation to pain appeared to be stronger among E-types than among M-types in respect to all pain dimensions. After adjustments, this was particularly seen in terms of NPS and pain frequency. Our findings suggest that eveningness intensifies the association between MSK pain and HRQoL, and, thus, they are indicative of E-types being more sensitive than M-types to the consequences of MSK pain. As such, MSK pain treatment and rehabilitation actions to improve HRQoL should be especially targeted at E-types.