0295 Association between circadian rhythm of skin temperature and actigraphic sleep in free-living conditions: the HEIJO-KYO study

Abstract

Abstract Introduction Skin temperature manipulation with little or no change in core body temperature affects sleep-wake states. However, the significance of 24-hour variation in skin temperature to sleep quality is unclear. We aimed to evaluate whether the circadian rhythm of distal skin temperature (DST) affects sleep quality in free-living conditions and to provide additional evidence about the relationship between thermal input to the skin and sleep-wake states. Methods In this cross-sectional study of 2,177 community-dwelling adults (Mean age 68.8 [SD 8.0] years), we measured DST using a temperature logger (Thermochron iButton, Maxim) at 3-minute intervals for seven consecutive days to calculate non-parametric indicators of circadian rhythm: intradaily variability (IV), interdaily stability (IS), and relative amplitude (RA). The participants underwent simultaneous 7-day wrist actigraphy (GT3X-BT, ActiGraph) to measure sleep objectively. The association between non-parametric indicators and 7-day means of sleep measures was evaluated using multivariable linear regression models. Results Lower quartiles of IV and higher quartiles of IS and RA were significantly associated with higher sleep efficiency, shorter wake after sleep onset, and longer total sleep time (all p <.001). After adjusting for potential confounders, including physical activity and outdoor temperature, the coefficients for the linear trend of sleep efficiency were −1.07 (95% confidence interval [CI]: −1.45, −0.69), 1.08 (95% CI: 0.75, 1.41), and 1.33 (95% CI: 0.83, 1.84) in IV, IS, and RA, respectively (all p <.001). Conclusion Circadian rhythms of DST with higher fluctuation, lower regularity across days, and blunted amplitude were associated with worse sleep quality. Our findings may be applied in thermoregulatory interventions to enhance sleep quality. Support (if any)