The blue light wavelength mostly comes from sunlight, but it is also produced by artificial light sources like those found on smartphones, as noted by WebMD. Past tests show that exposure to blue light, particularly later in the day when it’s time to go to bed, can affect the quality of your sleep. According to the Sleep Foundation, blue light disrupts the release of melatonin, the hormone responsible for making you feel sleepy. While this is beneficial during the day when we are active, it’s not a good thing when night falls and you need to get quality shut-eye.
After the sun goes down, blue light messes up the body’s natural circadian rhythm, which can lead to health problems such as obesity, cancer, heart disease, and diabetes (via Harvard). Additionally, blue lights may put your eyesight at risk. Studies have found that out of all the lights in the spectrum, blue light carries the most energy and can cause eye damage if you are overexposed to it (via Nature).