Only 20 years ago, scientists discovered we have a 3rd type of non-vision-related light receptors in our eyes: Intrinsically photosensitive retinal ganglion cells (what a mouthful... err... eyeful?) We also have a "chemical clock" in every cell nucleus that controls our circadian rhythm (2017 Nobel prize for this discovery!)
Robust circadian rhythms are important for good health. Exposure to blue light at night disrupts our circadian rhythms.