14 Reasons You Still Can't Sleep

You know those tiny particles that float by on window-filtered sunbeams? At night, they can trigger allergies and asthma flare-ups. Air purifiers banish dust and other allergens (like dry-cleaning chemicals from the bag hanging on your closet door), and dehumidifiers may also help by taking moisture out of the air. "More moisture means more allergens," says Collop. But at the opposite extreme, desert-dry air can cause a parched throat and itchy eyes, especially if you have a cold. Take into account the levels in your home, the climate where you live and the season when deciding how you should treat the air around you. The EPA recommends a household relative humidity of 30 to 50 percent, and you can test yours using a hygrometer (some thermostats have them built in, or you can buy an inexpensive one at a hardware store).