Wrist temperature: A circadian predictor of lipid profiles in arctic residents

Disruptions in circadian rhythms have been linked to adverse metabolic outcomes. This study investigated the relationship between circadian parameters of wrist temperature (wT) and lipid profiles in Arctic residents, a population characterized by extreme photoperiodic variation. We examined associations between the MESOR, amplitude and acrophase of wT and total cholesterol (TC), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C), triglycerides (TG), and the TG/HDL-C ratio in both Native (N) and non-Native (NN) individuals, utilizing photoperiod-adjusted regression models. Analyses followed two sampling strategies: all records (n varying between 35 and 64, depending on season), and records from participants sampled in each season (seasonally balanced sample: <i>n</i> = 27). In NN individuals, a larger wT amplitude was significantly associated with lower TC, LDL-C, and body mass index. The MTNR1B rs10830963 genotype modulated the relationship between wT amplitude and lipid parameters: a smaller wT amplitude was significantly associated with higher TC in individuals with the CC genotype, whereas a larger wT amplitude was significantly associated with higher HDL-C and lower TG/HDL-C in individuals with the CG+GG genotypes. A higher wT MESOR was associated with lower TG and TG/HDL-C ratio in NN individuals. An earlier wT acrophase was associated with higher TC and LDL-C in NN individuals. While, as expected, an earlier wT acrophase was associated with higher Morningness-Eveningness Questionnaire (MEQ) scores, indicative of greater morningness, surprisingly, an earlier wT acrophase was associated with higher TC and LDL-C in NN individuals. A lower MEQ score was a strong significant predictor of adverse lipid profiles exclusively in N individuals, whereas in NN individuals, the relationship with TC/LDL-C was reversed, i.e. higher TC/LDL-C was associated with an earlier wT acrophase, and an earlier phase angle between the wT acrophase and mid-sleep. Overall, circadian rhythms, as characterized by circadian parameters of wT and chronotype, are linked to lipid profiles in Arctic residents, highlighting the potential of wT circadian parameters serving as potential markers of metabolic health.