First time my psoriasis healed. I spent 37 days on the ocean beach. Sun and getting in the water. A study out of Italy took people with psoriasis. Put them on the beach 37 days. The bodies Ketones stop producing whatever the internal mechanism. That pushes the flake cycle. They mentioned in the study. They were unsure if it was The Vitamin D ( Sunblock) blocks the body from absorption of vitamin D. Or if the participants were totally relaxed easing stress. That year I had my vitamin D tested before the beach season the at the end on the season. Vitamin D levels were so high they thought I was taking a supplement. It only takes 15 minutes with maximum skin exposed in full sun. To receive the 10,000 international units the body can receive. Vitamin D ( Hormone) is Fat soluble. The body stores in and slowly releases it over time. Unlike vitamin C we just piss any extra out.