Our body’s master clock, or the SCN (suprachiasmatic nuclei), directly responds to light, and is the reason why we have sleep-wake cycles that are determined by light exposure. Artificial light disrupts this clock and its circadian rhythms, which may contribute to chronic insomnia, as well as other chronic diseases such as diabetes, obesity, heart disease, and cancer. Under the wrong light, your body is confused about what to do when and starts doing them at the wrong time.