Evening chronotype and disability pensions: 12-year register-based follow-up of middle-aged adults from the Northern Finland birth cohort 1966

Objectives Evening chronotypes (E) generally have poorer health than morning chronotypes (M), but whether this translates into disability pensions (DPs) is poorly known. We examined whether chronotype at age 46 predicts incident DPs over a 12-year follow-up. Methods In 2012, we determined chronotype among the non-retired participants of the Northern Finland Birth Cohort 1966 (n=5679) using the short Morningness-Eveningness Questionnaire, further validated by comparing the participants' survey scores at age 46 with their polygenic scores for morningness (PGSmorn) at age 31 (n=5130). We used Cox regression to calculate HRs with 95% CIs of incident DPs until age 57 (years 2012-2023), adjusting for factors related to socioeconomic status, health, sleep and working times at age 46. Results In total, 253 men (9.7%) and 381 women (12.4%) were E-types. The PGSmorn correlated with the chronotype (p<0.001). During follow-up, 135 men (5.2%) and 249 women (8.1%) were granted their first DP. For E-types, the corresponding proportions were 8.3% and 12.1%, respectively. Compared with M-types, the unadjusted HRs (95% CIs) for DPs among E-types were 1.72 (1.04 to 2.83) in men and 1.73 (1.22 to 2.46) in women. Adjusting for socioeconomic factors did not attenuate the results. Conclusions The higher incidence of DPs among E-types in the core productive years of work careers represents a major challenge for sustainable national economies. Further research and action to support health and work ability among E-types are needed.