The skin uses sunlight to help manufacture vitamin D, which is important for normal bone formation. But sometimes its ultraviolet light can be very detrimental.
Within the skin's epidermal (outer) layer are cells that contain the pigment melanin. Melanin protects skin from the sun's ultraviolet rays, which can burn the skin, and over time, could reduce its elasticity and cause a person to age prematurely. Suntanning occurs because exposure to sunlight causes the skin to produce more melanin and to darken. The tan fades as these cells move toward the surface and are sloughed off.
Too much exposure to ultraviolet or UV rays can cause sunburn. UV rays penetrate the outer skin layers and pass into the deeper layers, where they can damage or kill skin cells. People who do not have much melanin and sun burn easily should protect themselves by covering up sensitive areas, wearing sun block, limiting their total exposure time, and limiting their sun exposure between the hours of 10 a.m. and 2 p.m.
Frequent and prolonged exposure to ultraviolet rays over many years is the chief cause of skin cancer. Examine skin regularly for development of suspicious growths or changes in an existing skin lesion. Early detection and treatment are key in increasing the cure rate for skin cancer.
Review Date 5/10/2019
Updated by: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.