Psoriasis is an autoimmune disease that causes the immune system to overproduce skin cells. This causes a buildup of reddened patches of skin cells, with silvery scales, that can become itchy and painful.
One type of treatment for psoriasis is the use of UVA and/or UVB light.
Sunlight is a natural source for both types of ultraviolet light. For some, sun exposure may improve the appearance of their psoriasis in the summer.
The UVB light in sunlight is effective at treating psoriasis, states the National Psoriasis Foundations. They say that UVA light works best when used in phototherapy treatments, where it can be boosted with a drug called psoralen.
Bruce Strober, MD, director of the Psoriasis and Psoriatic Arthritis Center at NYU Medical Center said, "In general, people with psoriasis do better in summer for two main reasons -- there's greater humidity, which helps keep the skin moist, and there's more sunlight exposure," according to WebMD.
Moisture from humidity in summer helps psoriasis patients by moisturizing the dry plaques of skin.
Strober went on to say that, although 90 percent of those with psoriasis see improvement with the sun, about 10 percent are extremely sun-sensitive, and may find it makes their psoriasis worse.
It is also important for those with psoriasis to be aware of any medications they are taking that may make their skin more sun-sensitive. They may be more susceptible to getting sunburn, which can flare their condition.
Everyone, including those with psoriasis, needs to wear sunscreen when out in the sun, and limit the amount of sun exposure they get.
The National Psoriasis Foundation suggests that those with psoriasis try short, multiple exposures to sunlight, instead of staying out for a longer period all at once.
“Start with five to 10 minutes of noontime sun daily. Gradually increase exposure time by 30 seconds if the skin tolerates it. To get the most from the sun, all affected areas should receive equal and adequate exposure.”