Circadian Activity and Sleep Associated With Blood Lipids in Arctic Residents

This longitudinal study of Arctic residents investigates how physical activity and sleep, known to be affected by extreme Arctic photoperiods, are linked to blood lipid profiles and thus cardiovascular disease risk in this particularly vulnerable population. We analyzed parametric and non-parametric actigraphy data of physical activity (PA) and sleep measures across three distinct photoperiods (winter solstice, spring equinox, and summer solstice) in a cohort of Arctic residents. Multiple regression models, adjusted for photoperiod, were employed to determine independent associations of PA and sleep parameters with total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG). Robust circadian rhythms in PA were significantly associated with improved lipid profiles. Specifically, lower intra-daily variability IV (β = 0.423, p < 0.001) and higher inter-daily stability IS (β = -0.263, p = 0.019) of PA, indicating stable and predictable daily activity patterns, were associated with lower TG and TG/HDL-C ratios. A greater amplitude of PA rhythms was also associated with lower TG (β = -0.345, p = 0.002). An earlier timing of daily activity (acrophase) was associated with higher TC and LDL-C (β = -0.492, p < 0.001), while earlier wake times (β = -0.309, p = 0.009) and higher sleep efficiency (β = 0.237, p = 0.011) were associated with higher HDL-C. These findings highlight the relevance of circadian rhythmicity in dyslipidemia management, particularly in extreme photoperiods, suggesting that lifestyle interventions promoting stable daily activity and sleep patterns may be associated with improved metabolic health and reduced cardiovascular risk.