Light therapy—or phototherapy, classically mentioned as heliotherapy—consists either of A.) exposure to sunlight or some equivalent sort of light as a treatment for seasonal major affective disorder (SAD) or B.) exposure of the skin to specific wavelengths of sunshine using polychromatic polarised light to treat a skin condition. As a treatment for wintertime seasonal major affective disorder , there's tentative evidence to support its use to treat non-seasonal psychiatric disorders, especially major depression and depression in manic depression . and is additionally utilized in biological time disorders like delayed sleep phase disorder. As a treatment for disorders of the skin, the second quite light therapy is supposed to correct psoriasis, acne , eczema and neonatal jaundice.