Beauty experts have been saying this for years, but Harvard University research confirms that prolonged or excessive exposure to sunlight is the major culprit behind aging skin. In fact, the researchers said that people who avoid the sun can look up to 20 years younger than those who are frequently exposed to it. The researchers examined 231 women of all ages for evidence of elastosis, which is the build-up of abnormal elastin (elastic tissue) from the cumulative effects of prolonged and excessive sun exposure. They found that no amount of exercise, extra sleep or drinking water could counter the aging effect of the sun. Unfortunately, the researchers said sun damage occurs not only at the beach but also on cloudy days and from light coming through the window.