1 in 3 Seniors Take Sleep Aids, Despite Dangers
One-third of older Americans take something to help them sleep, but most don't discuss their sleep problems with a doctor, a new survey finds.

During normal sleep, you cycle through REM and four stages of non-REM (NREM) sleep numerous times a night. Stage 1 of NREM sleep is the lightest, while stage 4 is the deepest. When you're repeatedly interrupted and can't cycle normally through these types and stages of sleep, you may feel tired, fatigued, and have trouble concentrating and paying attention while you're awake. Sleepiness puts you at greater risk for car wrecks and other accidents.

What Are Sleep Disorders? Circadian Rhythm Disorders Typically, people sleep at night -- thanks not only to the conventions of the 9-to-5 workday, but also to the close interaction between our natural sleep and alertness rhythms, which are driven by an internal "clock." This clock is a small part of the brain called the suprachiasmatic nucleus of the hypothalamus. It sits just above the nerves leaving the back of our eyes. Light and exercise "reset" the clock and can move it forward or backward. Abnormalities related to this clock are called circadian rhythm disorders ("circa" means "about," and "dies" means "day").