B. Listen to a talk about light and health. Take notes and complete the following summary. Many researchers believe that 1 can 2 both your 3 and your 4 . From daylight, our bodies 5 through the skin. Certain 6 diseases also 7 from 8 to 9 . Light absorbed through the 10 can 11 production, which in turn 12 our 13 . Some people become 14 in 15 , when the days are16___ and most people spend 17 in the open air. When spring comes, these symptoms 18 . Researchers have called this condition SAD —19 _________. The condition can be 20 by 21 patients to special lights, known as22______. This lighting has also been used to treat patients suffering from 23 , to improve 24 in school-children in Russia and America, and the 25 of Japanese factory workers. Young people need at least 26 a day in 27____ in 28 , 29 in 30 Old people, who risk 31 , should spend even 32 exposed to33_____ daylight.