UV light has antimicrobial properties and has a positive effect on the immune system. It encourages wounded tissue to heal and is effective for treating ulcers, candida albicans, psoriasis, infections like MRSA, and localized scleroderma. UV light is also effective treatment for those who suffer from Seasonal Affective Disorder (SAD), a type of depression common during winter months when there is less sunshine. A factor in vitamin D production, sensible UV exposure time is necessary to prevent damage to skin and eyes.