The U.S. National Institute of Diabetes and Digestive and Kidney Diseases has reviewed existing scientific findings on light exposure and its impact on the human body. It confirmed that light exposure plays a critical role in regulating basic physiological functions such as sleep-wake cycles, physical activity, eating habits, body temperature, and energy metabolism. Disruption of these processes due to inappropriate light exposure can lead to metabolic dysfunctions, increasing the risk of obesity and diabetes. Light affects the human body through circadian rhythms, with key factors including light intensity, exposure duration, spectral composition, and timing of exposure. Melatonin, a hormone involved not only in sleep regulation but also in metabolic processes, is an essential mediator of these physiological mechanisms, and its production depends on light exposure. Therefore, optimal light exposure that aligns with natural sunlight is crucial for preventing negative health consequences.
Overuse of artificial light sources in the evening disrupts the natural day and night cycles of the human body
Increased light exposure at night and reduced dynamic range of light between day and night disrupt the natural human circadian rhythm, negatively affecting sleep, energy intake and expenditure. The production of the sleep hormone melatonin is affected by light conditions. Disruption of proper melatonin production is associated with metabolic disorders such as increased risk of obesity and diabetes. Although individuals respond differently to evening light, according to the NIDDK document, adjusting lighting conditions so that they mimic sunlight, or melatonin supplements, can help mitigate the negative effects of irregular light exposure, especially in people with disrupted circadian rhythms.
