Natural sunlight contains many wavelengths of light besides visible light: invisible ultraviolet radiation is present as well. Ultraviolet radiation is often used to treat psoriasis in the doctor's office using special equipment. Heliotherapy (also called climatotherapy) makes simple use of intentional direct exposure to natural sunlight to get the therapeutic benefits of the included ultraviolet radiation.
The use of heliotherapy began a long time ago when it was used in India, China and Egypt to treat diseases, including psoriasis. Ancient Greeks also used natural sunlight as therapy. As far back as 3,000 years, medical practitioners were advanced enough to use sunlight-sensitizing chemicals before sun exposure - a primitive version of today's photochemotherapy or PUVA. Heliotherapy has been studied, and it works. Benefits lasting beyond a year have even been documented.
Words of Caution
The same invisible ultraviolet radiation that treats psoriasis is also responsible for many undesirable skin changes as well. These same wavelengths of light can also cause skin aging, wrinkling, tanning, burning and skin cancer. For this reason, heliotherapy should be applied with the same caution, forethought and examination of risks, benefits, and alternatives as any other psoriasis therapy.
Heliotherapy should be avoided by anyone with a history of alcoholism or serious mental health issues, as well as those taking photosensitizing medications. Careful exposure to noonday sun -- for short periods at first, and longer periods as tolerated -- should give significant results in as little as 3 to 4 weeks. Inform your physician if you plan to use heliotherapy to be certain that it will not conflict with any of your other medications. For those willing to travel for a supervised course of heliotherapy, spas at the Dead Sea in Israel offer what is generally considered the ultimate heliotherapy experience.
Sources:
The History of Photodetection and Photodynamic Therapy
Supervised four-week heliotherapy alleviates the long-term course of psoriasis
Effect of Heliotherapy on skin and joint symptoms in psoriasis: a 6-month follow-up study
