If you spend a nightmarish amount of time in the wee hours counting sheep or wrestling with your pillow—or your worries—you've got lots of company: Up to 70 million Americans either have a sleep disorder or are sleep-deprived. For some of us, it's a physical problem, such as sleep apnea (a brief cessation of air flow). For others, it's caused by emotional or environmental factors. Brush up on these basic rules to getting a good night's sleep.

Be consistent. If you sleep short all week and try to catch up on weekends, you'll never be well-rested. Aim for seven to eight hours every night.

Exercise regularly. Working out not only reduces stress that can keep you awake, it lessens the symptoms of PMS and lengthens slow-wave (the deepest) sleep. But be sure to quit exercising at least four hours before bedtime, because it raises body temperature and adrenaline levels.

Cut out caffeine and quit smoking.. Caffeine and nicotine are short-acting stimulants that disrupt sleep.

Nix the nightcap. Alcohol disturbs the way your body flows from one stage of sleep into the next, which is why if you drink before bed, you may wake up with a start in the middle of the night and have trouble getting back to sleep.

Turn off the TV. Although television is sedating, it simply numbs your mind, postponing stressful thoughts until later in the evening.

Set aside "worry time" earlier in the day. Don't wait until you turn off the light to put together your to-do list.

Get medical advice. If you've tried all the suggestions above but still have trouble sleeping, consult your doctor or contact a sleep disorders clinic. Look for one that's accredited by the American Academy of Sleep Medicine. To find a center in your area, call 708-492-0930 or visit www.aasmnet.org.