What is light therapy?

Sleep treatment: Our tendency to feel sleepy at certain times and awake other times are strongly influenced by natural body rhythms called the sleep wake circadian rhythm. This sleep and wake cycle is strongly affected by the light that enters our eyes. Carefully timed light therapy allows physicians to adjust an individuals rhythm so that they feel more awake and alert.

Ultraviolet light: think you're referring to tx for various skin diseases, incl psoriasis. There are diff types of uvl, some more beneficial and safer than others. see your dermatologist for evaluation of your problem.