Blue Light and Temperature Actigraphy Measures Predicting Metabolic Health Are Linked to Melatonin Receptor Polymorphism

Abstract

This study explores the relationship between the light features of the Arctic spring equinox and circadian rhythms, sleep and metabolic health. Residents (N = 62) provided week-long actigraphy measures, including light exposure, which were related to body mass index (BMI), leptin and cortisol. Lower wrist temperature (wT) and higher evening blue light exposure (BLE), expressed as a novel index, the nocturnal excess index (NEIbl), were the most sensitive actigraphy measures associated with BMI. A higher BMI was linked to nocturnal BLE within distinct time windows. These associations were present specifically in carriers of the MTNR1B rs10830963 G-allele. A larger wake-after-sleep onset (WASO), smaller 24 h amplitude and earlier phase of the activity rhythm were associated with higher leptin. Higher cortisol was associated with an earlier M10 onset of BLE and with our other novel index, the Daylight Deficit Index of blue light, DDIbl. We also found sex-, age- and population-dependent differences in the parametric and non-parametric indices of BLE, wT and physical activity, while there were no differences in any sleep characteristics. Overall, this study determined sensitive actigraphy markers of light exposure and wT predictive of metabolic health and showed that these markers are linked to melatonin receptor polymorphism.

Comparison of Ten Surrogate Insulin Resistance and Obesity Markers to Identify Metabolic Syndrome in Mexican Adults

“…Triglycerides' sensitivity as a biomarker can be attributed to circadian factors (note that metabolic syndrome can even be considered circadian syndrome [44,45]). Nocturnal eating habits and compromised metabolic health are closely associated with an evening chronotype [46] and exposure to evening light [47], which may also contribute to the development of metabolic syndrome [48]. Furthermore, lipid measurements such as triglycerides or HDL sampled at a fixed morning time may vary depending on individual circadian phase differences, such as melatonin secretion or light exposure (e.g., [49]).…”

Overview of wearable light loggers: State-of-the-art and outlook

“…Wearable light loggers have become instrumental in A advancing field research across domains such as architectural lighting, public health, circadian and sleep science, and psychology, focusing on behavioral outcomes related to light exposure in real-world settings. Multiple studies have now leveraged wearable light logger data from free-living individuals to better characterize light exposure patterns across populations [9][10] [11][12] and connect light exposure measures to physiological and behavioral indicators such as sleep [13], mood [14], alertness [15][16], metabolic health [17][18], academic performance [19], and myopia development and progression [20]. Collectively, findings underscore roles for both acute light exposures and chronic circadian light-dark rhythms in driving outcomes like psychiatric disorders [21], obesity [22] and sleep-wake consolidation in older adults [23].…”