Scientists measure brightness in something called lux. We've learned that we need exposure to light that is between 1000-2000 lux to keep our body clocks ticking over. In the middle of your living room, with all the lights on, the brightness will be about 200-300 lux. But when you step outside, even on a dim day the brightness will be about 10,000 lux. Exposure to light will not only prevent sleep problems, it may also be crucial for keeping our brains in good shape. This is especially important to people as they begin to age. As we age our eyes become less sensitive to light, so older people need to be exposed to three to five times more light then younger people, to ensure their biological clocks are kept in sync. So be sure to spend some time outside everyday. You'll not only sleep better but also help to keep your brain in tip top shape.
Many sleep researchers now believe that it is important to get outside everyday especially in the winter. The best time is actually first thing in the morning because this is when our body clock is most responsive to light. We've found that the best practice is to throw open those curtains the minute you wake up and sit near a window to eat breakfast. Then, no matter what the weather, try to get outside.