The "UV free" designation means that the lamp does not emit ultraviolet radiation, commonly referred to as UV radiation, when lit. This radiation is a natural part of sunlight, but can be harmful to the skin and eyes with prolonged exposure. The purpose of a light therapy lamp is to provide only intense visible light that affects biorhythms and mood, not the UV component intended for, for example, sunbathing. By filtering out the UV radiation, the lamp is safe to use and the user is only exposed to the part of the light spectrum that is desirable for the therapy itself.