Learn about the cause of sunburns, in this video from NOVA’s Gross Science series. Sunlight is made up of many types of radiation: infrared, visible, and ultraviolet (UV). UV radiation can damage skin cells by causing mutations in DNA. Skin cells naturally produce melanin, which absorbs UV light and acts as a natural sunscreen. Exposure to sunlight can trigger the production of more melanin, which is why skin becomes darker (tanned). However, UV radiation can penetrate the body’s natural defenses and damage DNA in skin cells. An inflammatory response to repair the damage causes redness and peeling skin—a sunburn. Damaged skin cells can develop into cancerous cells. This resource is part of the NOVA: Gross Science Collection.