For about 90 percent of those with psoriasis, summertime can bring with it a reprieve from unpleasant symptoms they live with year-round.
Bruce Strober, MD, director of the Psoriasis and Psoriatic Arthritis Center at NYU Medical Center attributes much of the summer benefits to greater exposure to sunlight's UVA rays and higher humidity, according to an article on WebMD.com.
Unlike the average person whose skin cells shed about once a month, being replaced by new cells, the skin cells of people with psoriasis are being replaced every two or three days. The old cells end up layered on top of the newer cells because of this rapidity. This is how psoriasis plaques are formed.
Strober said that humidity in the air helps to ease dry skin plaques. And he said that UVA rays from the sun can ease psoriasis symptoms.
Unfortunately approximately 10 percent of people with psoriasis get worse from sun exposure. They may benefit from the higher humidity but the sun is not their friend.
Phototherapy is an accepted treatment for psoriasis which is normally performed in a doctor's office, clinic or at home. This treatment can use UVA or UVB rays from an artificial light source, administered on a regular schedule.
Psoriasis.org reported that UVB rays from the sun penetrate the skin, slowing skin cell growth for some with psoriasis. The website recommends a short exposure to the sun at first, gradually increasing exposure time.
Strober recommended that a person with psoriasis spend up to half an hour a day in the sunshine. He cautioned that too much sun, especially if it results in sunburn, can make psoriasis plaques worse, and can create new ones as well.
Ellen Marmur, MD, chief of dermatologic and cosmetic surgery at Mount Sinai Medical Center in New York City, suggested that plenty of sunscreen or sunblock be applied regulary to prevent skin damage.
Marmur explained that sunblock protects against both UVA and UVB rays, while most sunscreen protects only against UVA rays. This is important to keep in mind, she said, to lower the risk of skin cancer and to lower the risk of cell damage that can trigger psoriasis flares.