Evening preference with evening-type rest-activity rhythm: a risk for poor quality of life.

backgroundChronotype reflects an individual’s intrinsic preference for the timing of activity and rest; however, perceived circadian preference may differ from actual behavioral rhythms due to external demands. Both chronotype and rest–activity rhythm have been linked to adverse health outcomes, but their combined association with health-related quality of life (HRQoL) has been less explored. This study investigated how combinations of circadian preference and objectively measured rest–activity timing relate to HRQoL.

methodsWe analyzed data from the Korean Medicine Daejeon Citizen Cohort, including participants who wore a Fitbit for ≥ 7 consecutive days. Chronotype was determined from the Morningness–Eveningness Questionnaire score quintiles, and rest–activity rhythm type from quintiles of the 5-h lowest activity period (L5 start time). Participants in intermediate quintiles were excluded. Four chronotype–rhythm groups were defined: MM (morning preference/morning rhythm), ME (morning preference/evening rhythm), EM (evening preference/morning rhythm), and EE (evening preference/evening rhythm). HRQoL was assessed using the SF-12 Physical Component Summary (PCS) and Mental Component Summary (MCS), the EQ-5D index, and the EQ Visual Analog Scale (VAS). Multiple linear and logistic regression analyses were conducted, adjusting for sociodemographic, lifestyle, and circadian rhythm variables.

resultsIn total, 458 adults were included in the analysis. Compared with the MM group, the EE group had significantly lower scores for PCS, MCS, EQ-5D index, and EQ VAS (all P < 0.05), which persisted after full adjustment. The EM group had lower MCS but no significant differences in other HRQoL measures. In SF-12 subscales, both EM and EE groups reported lower general health and vitality, while only the EE group had lower role-physical and role-emotional scores. In EQ-5D dimensions, the EE group was more likely to report moderate to extreme pain/discomfort.

conclusionsEvening preference combined with an evening-type rhythm was associated with consistently poor HRQoL across physical, mental, and health utility domains, independent of confounders including activity levels, circadian robustness, social jetlag, and variability in sleep onset timing. Alignment between preference and rhythm did not confer benefit in the context of eveningness and may be disadvantageous in morning-oriented societies. Future longitudinal studies should examine underlying mechanisms and potential intervention strategies.