Don't Have a Night Light

"After-hours brightness could even affect your weight. In a study published in October, researchers at Ohio State University exposed one group of mice to a dim light at night, while another group was allowed to experience a standard day-night cycle. Over two months, the first group gained 50 percent more weight than the second group—even though both ate the same amount of food and had similar activity levels. The only difference was that the first group began eating at unnatural times—when their digestive systems were not keyed to metabolize food."

http://www.oprah.com/health/The-Negative-Effects-of-Sleep-Loss/1