Why Do We Get Sunburned?

When ultraviolet B (UV-B) radiation from the Sun penetrates the skin, it damages the DNA in epidermal cells by creating thymine dimers — abnormal bonds between adjacent bases in the DNA strand. The body responds with an inflammatory cascade: blood vessels dilate (causing redness), immune cells rush to the area, and damaged cells may undergo programmed death (apoptosis) — peeling is the body shedding these dead cells. Melanin, the pigment produced by melanocytes, absorbs UV radiation and provides natural protection, which is why people with more melanin tan rather than burn. Repeated UV damage accumulates and increases the risk of skin cancer.