Sunbeds are machines designed to emit ultraviolet (UV) radiation. This UV radiation has the same damaging effects on your skin as natural sunlight and, as it is unnecessary exposure, should be avoided at all times. Tanning on a sunbed does not provide a better base for later additional tanning in the sun, and there is no such thing as a safe tan. The use of sunbeds to increase your vitamin D level is unnecessary and is strongly discouraged. The same type of UV radiation induces a suntan as also increases your risk of skin cancer and damages your skin in the ways described earlier.
Some people consider that their use of sunbeds helps to treat winter depression, but this can be done more safely by using bright visible-light lamps that do not emit UV radiation. People who require medical UV treatment for a disease should be treated under close medical supervision, for instance in clinical settings. Sunbeds are sometimes marketed to treat a variety of complaints and diseases (e.g., neurodermatitis, acne, high blood pressure) or to improve immune responses. Any use for medical reasons should, however, be prescribed and supervised by a physician.