Blue light can be used for the treatment of neonatal jaundice, anti-inflammatory, anti-aging and so on. 1. Treatment of neonatal jaundice: blue light irradiation is a simple and effective method commonly used in the treatment of neonatal jaundice. Excessive bilirubin is the main cause of neonatal jaundice, and bilirubin can absorb the light with a spectral range of 400-500nm, which can be converted into other substances, and the symptoms of jaundice can be improved by irradiating blue light. 2. Anti-inflammatory: Blue light can induce vasodilatation to release white blood cells, which can prevent or improve inflammatory reactions and promote skin healing. 3. Anti-aging: Blue light can accelerate cell growth, stimulate cells to produce collagen, and play the role of anti-aging.