Psoriasis is caused due to the immune system reaction where the T cells in the body starts uncontrolled division of skin cells and skin cells accumulate over each other resulting in formation of scales. Actually psoriasis cannot be cured but the rate of its progress can be slowed down. When skin of the psoriasis affected person is subjected to UV light which can be directly from the sun or artificial source, a biological process is set off in the body which kills the T cells and slows down the rate of division of skin cells and reduces the building up of skin cells.

This treatment helps to reduce inflammation. For the treatment, a person has to get into a light box whose size is equal to that of the telephone booth. Inside it a lamp directs the light on the body of the psoriasis affected person. This treatment is not risk free and its overexposure may lead to diseases such as skin cancer, premature aging, darkening of skin and burning sensation. Per week three to five doses of ultraviolet treatment are needed to keep psoriasis under control followed by weekly maintenance treatments.