Your eyes pop open at 2 or 3 AM, and try as you might, you just can't fall back asleep. Sound familiar? "Everyone has an occasional restless night," says Timothy Morgenthaler, MD, president-elect of the American Academy of Sleep Medicine. "But if you regularly find it hard to get back to sleep within 15 or 20 minutes, or if you wake up more than two or three times per night, that can cause disruption in your daily life and is worth addressing."