Think you do just fine on five or six hours of shut-eye? Chances are, you are among the many millions who unwittingly shortchange themselves on sleep. Research shows that most people require seven or eight hours of sleep to function optimally. Failing to get enough sleep night after night can compromise your health and may even shorten your life. From infancy to old age, the effects of inadequate sleep can profoundly affect memory, learning, creativity, productivity and emoti