15 shortcuts to getting fit, healthy

You know to brush your teeth and apply sunscreen at certain times of the day. But did you know that having a Pap smear at the right time in your menstrual cycle can improve the test's accuracy? Or that working out is easier at particular hours? As chronobiologists—experts in the science of biological rhythms—are discovering, timing is everything when it comes to our health and happiness. So get out your day planner and mark down the following:

1. Take vitamin and mineral supplements with meals, says Leslie Bonci, R.D., director of the sports medicine nutrition program at the University of Pittsburgh Medical Center. "Your body produces more acid while you're eating, which helps absorption. Also, the pill dissolves more thoroughly when your stomach is full."

2. Eat dinner at least four hours before bedtime. This will ensure more efficient digestion and — because too much food at bedtime interferes with sleep — help you sleep better.

3. Schedule allergy skin tests for as late in the day as possible, when these tests are likely to be the most accurate. The skin reacts as much as two times more strongly to an allergy in the late afternoon and evening.

4. See a doctor at the time of day when symptoms are most severe, so he or she can more accurately assess your condition. For example, asthma sufferers should seek help first thing in the morning, when airway function is poorest.

5. Pump iron between 4 p.m. and 8 p.m., says Michele S. Olson, Ph.D., a professor of exercise physiology at Auburn University in Montgomery, Ala. Because your peak all-around athletic performance occurs at this time (heart and lungs are strongest, muscles are most flexible and reflexes are fastest), any strength-training activity — using free weights, machines or your own body — is best done then.

6. Play basketball, run, dance anytime except days 10 through 14 of your menstrual cycle. According to a study of young women with damage to the anterior cruciate ligament, which runs through the center of the knee joint and controls its pivoting motion, those days may be a vulnerable time for this type of knee injury.

7. Quit smoking in the first half of your menstrual cycle. Those who go cold turkey at that time suffer less severe nicotine-withdrawal symptoms, reports Kenneth Perkins, Ph.D., a professor of psychiatry at the University of Pittsburgh School of Medicine, who studied the phenomenon. The side effects of quitting, he says, are so similar to symptoms of PMS that a combination of the two may deliver a double dose of misery.

8. Undergo any painful procedure — be it leg waxing or dental surgery — right after ovulation, when pain tolerance is highest. (As women who get cramps probably already know, it's lowest during menstruation.)

9. Read for comprehension in the afternoon, when long-term memory peaks.

10. Concentrate mid- to late morning. It's also a good time for demanding tasks and meetings, says Dr. Michael Smolensky of the University of Texas School of Public Health, since we feel especially social then.

11. Weigh yourself in the morning (after you make a trip to the bathroom, that is). That's when body weight is at its daily low.

12. Measure your height depending on whether you prefer to be a smidgen taller (as you are in the a.m.) or shorter (as you are in the p.m.). The reason: Lying down allows vertebrae to separate slightly, adding height.

13. Shop for shoes at the end of the day or 30 to 60 minutes after a workout, when feet are at their biggest, suggests Carol Frey, M.D., director of the Orthopaedic Foot and Ankle Center in Manhattan Beach, Calif.

14. Diet in the spring and summer. At least that's when it will be the easiest to lose weight. According to Smolensky, body rhythms cause most of us to gain a few pounds in the fall and winter. "This pattern probably helped our ancestors survive the winter when food was scarce. But it makes maintaining weight harder when food is plentiful year-round."

15. Sleep between 10 p.m. and 6 a.m. "Research suggests that if you normally need eight hours of sleep and you get them between these hours, you'll actually feel more rested than if you go to sleep at midnight and get up at 8 a.m.," says David Simon, M.D., medical director of the Chopra Center for Well Being in La Jolla, Calif, and author of "Vital Energy" (John Wiley & Sons, 2000).

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