Can Light Affect Your Health? Many researchers believe that light can affect both your physical and your ( 1 ) . From daylight, our bodies absorb vitamin D through the skin. Certain skin diseases also ( 2 ) from exposure to sunlight. Light absorbed through the eye can stimulate hormone production, which in turn ( 3 ) our mood. Some people become ( 4 ) in winter, when the days are dark and most people spend less time in the open air. When spring comes, these ( 5 ) disappear. Researchers have called this condition SAD -- seasonal affective depression. The condition can be ( 6 ) by exposing patients to special lights, known as full-spectrum lights.This lighting has also been used to treat patients ( 7 ) from jet-lag, to improve learning in school-children in Russia and America,and the ( 8 ) of Japanese factory workers . Young people need at least fifteen minutes a day in real daylight in Summer ( 9 ) in winter. Old people, who risk vitamin D deficiency, should spend even longer exposed to ( 10 ) daylight.