Why is it so difficult to fall asleep when you are overtired? There is no one answer that applies to every individual. But many people fail to note the distinction between fatigue physical tiredness and sleepiness, the inability to stay awake. It’s possible to feel “tired” physically and still be unable to fall asleep, because while your body may be exhausted, you don’t feel sleepy. To fall asleep, you need adequate time to unwind1, even if you feel fatigued. It’s not so easy to simply “turn off.”

　　According to Carl E. Hunt, director of the National Center on Sleep Disorders Research in Bethesda, Maryland, most people do not allow themselves sufficient deceleration2.

　　Lack of sleep complicates matters even more. Experts say adults need at least 7 to 8 hours of sleep a night to function properly. When you get less sleep than that on consecutive3 nights, you begin to accrue4 “sleep debt.” As sleep debt increases (and functionality decreases), your body experiences a stress response and begins to release adrenaline5. Now a vicious cycle has been created: You experience the feeling of being more and more tired, but your body is increasingly stimulated. “Power sleeping” for more hours on weekends is only a temporary solution. “There is no substitute for getting a good night’s sleep on a regular basis,” says Hunt.

　　Most of us, however, don’t get the sleep we need. According to the 2002 National Sleep Foundation, Americans sleep an average of 6.9 hours per night during the week, and 58 percent of adults experience symptoms of insomnia6 a few nights a week or more.