Suppression of Blue Light at Night Ameliorates Metabolic Abnormalities by Controlling Circadian Rhythms

Abstract

PURPOSE. Light-emitting diodes that emit high-intensity blue light are associated with blue-light hazard. Here, we report that blue light disturbs circadian rhythms by interfering with the clock gene in the suprachiasmatic nucleus (SCN) and that suppression of blue light at night ameliorates metabolic abnormalities by controlling circadian rhythms. METHODS. C57BL/6J mice were exposed to 10-lux light for 30 minutes at Zeitgeber time 14 for light pulse with blue light or blue-light cut light to induce phase shift of circadian rhythms. Phase shift, clock gene expression in SCN, and metabolic parameters were analyzed. In the clinical study, healthy participants wore blue-light shield eyewear for 2 to 3 hours before bed. Anthropometric data analyses, laboratory tests, and sleep quality questionnaires were performed before and after the study. RESULTS. In mice, phase shift induced with a blue-light cut light pulse was significantly shorter than that induced with a white light pulse. The phase of Per2 expression in the SCN was also delayed after a white light pulse. Moreover, blood glucose levels 48 hours after the white light pulse were higher than those after the blue-cut light pulse. Irs2 expression in the liver was decreased with white light but significantly recovered with the blue-cut light pulse. In a clinical study, after 1 month of wearing blue-light shield eyeglasses, there were improvements in fasting plasma glucose levels, insulin resistance, and sleep quality. CONCLUSIONS. Our results suggest that suppression of blue light at night effectively maintains circadian rhythms and metabolism.

Long-Term Narrowband Lighting Influences Activity but Not Intrinsically Photosensitive Retinal Ganglion Cell-Driven Pupil Responses

“…Several studies in humans have shown that increased exposure to short-wavelength light in the evening suppresses melatonin secretion ( Cajochen et al, 2005 ; Chellappa et al, 2011 ; Lee et al, 2018 ), increases alertness at night ( Cajochen et al, 2005 ; Figueiro et al, 2009 ), and can affect sleep architecture as measured with electroencephalography ( Münch et al, 2006 ; Chellappa et al, 2013 ). In contrast, filtering out short wavelengths at night has been reported to increase melatonin levels and improve sleep efficacy, quality, and latency in humans ( Burkhart and Phelps, 2009 ; Ayaki et al, 2016 ; Ostrin et al, 2017 ; Nagai et al, 2019 ). Contrary to what we expected, monkeys reared in blue light exhibited lower activity during the first hour and greater activity during the final hour of the lights-off period compared to white and red light reared monkeys, suggesting shorter sleep latency and earlier wake-up time.…”

Associations of PER3 polymorphisms with clopidogrel resistance among Chinese Han people treated with clopidogrel

“…The circadian rhythm is essential for regulating all aspects of physiology, such as blood sugar in the endocrine system and inflammatory cells in the immune system. [27][28][29][30] Studies show that changes in biological rhythms can affect the body's physiological activities. The PER3 gene has been proven to be one of the very important clock genes in the human body, and it can affect downstream physiological activity changes by regulating sleep rhythm.…”

“…The circadian rhythm is essential for regulating all aspects of physiology, such as blood sugar in the endocrine system and inflammatory cells in the immune system 27‐30 . Studies show that changes in biological rhythms can affect the body's physiological activities.…”

The light-curing unit: An essential piece of dental equipment

“…Most contemporary dental LED curing lights emit light between 430 and 480 nm, and the most damaging wavelengths of blue light to the retina are thought to be around 440 nm 69 . Exposure to blue light has also been reported to affect sleep patterns 25,70,71 . Although a 'blue light hazard' to the retina has not yet been shown to occur in humans, dental personnel may be both chronically and acutely exposed to much greater high levels of blue light than the general population.…”