Natural sunlight the suns ultraviolet rays are made up of uva and uvb rays uvb rays are more effective at treating psoriasis symptoms because they slow the rapid rate of skin growth and shedding. Controlled sun exposure may help with psoriasis the sun emits ultraviolet uv rays which can be uva or uvb the difference lies in the size of the wavelength uva rays can reach deeper into the. Uva light by itself doesnt do much to ease psoriasis symptoms but uvb light can slow down the growth of your skin cells which helps with scaling and inflammation uvb also helps your body make. So sunlight can help psoriasis by virtue of the uvb wavelengths it contains the uvb wavelengths in sunlight are also very effective at causing the production of vitamin d in the skin vitamin d is essential for bone and skin health for more information about the use of artificial sunlight see psoriasis and phototherapy