Blue Light. As you know, light consists of a range of colours. Each colour has a different energy frequency or wavelength. The graph below shows this spectrum. Blue light down to violet and ultra violet (UV) light has a powerful effect on the human body. From an evolutionary perspective we only experienced blue or UV light during the day (from the sun). When there was no blue light present it meant sundown and darkness. However today, we are flooded in blue light 24/7. We carry artificial suns in our pockets. Every time we look at our smartphone we send a signal to the brain that the sun is up. This impacts our circadian rhythm, our sleep, and our health.