Birds do it. Bees do it. Even blue-green bacteria do it—tell time, that is, thanks to an internal clock that helps trigger migration, pollination, and, well, all those things that bacteria do. What’s even more surprising is that your body follows a clock, too, whether or not you wear a watch on your wrist. Your blood pressure, your stamina during exercise, and your tendency to sneeze or wheeze—just about every biological process sticks to some kind of daily or seasonal rhythm.
What that means: You can improve your health with barely any effort—if you know how to use the power of your body’s daily, weekly, and seasonal cycles. To feel better now, here’s the right time to …
1. Get the best medical care.
Have a cavity filled in the afternoon
The painkilling effect of dental anesthesia lasts longer in the afternoon than it does in the morning. In one study, lidocaine kept nerves numb up to five times longer when it was injected in the early afternoon compared with early morning.
Check your blood pressure in the morning and at night.
As a general rule, blood pressure fluctuates throughout the day—it hits its lowest point around bedtime and its highest when you wake in the morning, says J. David Glass, PhD, a circadian biologist at Kent State University. If you’re keeping an eye on your blood pressure to help your doctor decide whether you need medication, you could get an inaccurate picture by taking your reading just once a day. “If you’re measuring it yourself, it’s best to do it in the morning and evening,” Glass says. “Be sure to do it at the same times each day—don’t bounce around.” Taking the two readings could make the difference between your doctor prescribing blood pressure drugs and advising you to stick with diet and exercise, he says.
2. Drop a few pounds.
Weigh yourself on Friday and Monday
For those trying to lose weight, experts have long suggested stepping on the scale at least once a week—that’s the habit of most members of the National Weight Control Registry, every one of whom has taken off at least 30 pounds and kept it off for a year or more. Now a new study from the Washington University School of Medicine ratchets things up. Dieters tend to splurge on weekends, the research found—but a Friday weigh-in (especially done first thing in the morning, when your weight is lowest) provides positive feedback that can blunt the temptation to overeat, says lead study author Susan Racette, PhD. And getting back on the scale on Monday can help you correct your course quickly if you’ve strayed, she says.
Eat dinner earlier
Recent research supports the folk wisdom that nighttime eating is more apt to add pounds. In one study, researchers fed one group of mice during their normal waking hours and a second group when the animals usually slept. The mice that ate at the “wrong” time gained more than twice as much weight. “If you think you’re doing everything right with your diet but you’re not losing, try having dinner an hour earlier,” says lead study author Deanna Arble, at Northwestern University. “It won’t hurt, and it might help.”
Exercise in the evening
If you want to get fit faster, a late-day workout is the most efficient way to go. Research by Michael Deschenes, PhD, an exercise physiologist at the College of William & Mary in Williamsburg, Virginia, shows that strength and endurance climb by about 5 percent between 4 and 8 p.m., compared with morning hours, so you can push yourself harder. Your muscles are warmer, too, which will help you avoid injury.
3. Protect your heart.
Take preventive medicines in the evening
Research suggests that a daily aspirin is less likely to cause stomach bleeding when taken late in the day. It’s even possible that this timing could protect you better. The reason: Your risk of heart attack spikes in the morning (the danger is nearly three times higher between 6 a.m. and noon than during the rest of the day). Aspirin helps cut clot risk by reducing platelet “stickiness”—a single tablet will take care of a platelet for its entire ten-day life span. But new platelets are being made all the time. Taking your aspirin at night ensures that you’ll have plenty of the drug to defang newly minted platelets during those potentially dangerous morning hours.
Get an extra hour of sleep next time you set the clock ahead
Nothing says spring is coming like the hour of sunlight you gain when daylight saving time begins—but your heart might pay for that pleasure. Swedish researchers have seen a 5 percent jump in heart attacks during the first week of daylight saving time, probably because of the loss of sleep and the disruption of bodily cycles. Next year, it may be beneficial to get to bed earlier on the night you switch your clock.
4. Cut down on sneezing and wheezing.
Get tested for asthma in the morning
Airways naturally become more constricted and inflamed in the dead of night (between 2 and 5 a.m.), so asthma attacks are most likely to strike then. “If you go to your doctor first thing in the morning, you’re likely to have a diagnostic test that’s most representative of your condition when it’s at its worst,” says Michael Smolensky, PhD, a professor of biomedical engineering at the University of Texas at Austin. (Your doctor may also ask you to use a peak flow meter at home so you can test yourself at your wheeziest.) Because women are most prone to severe asthma flare-ups on the days before their period, that’s also a good time to monitor symptoms and keep meds handy.
Take allergy medication in the evening
Hay fever symptoms such as runny nose, scratchy throat, and sneezing typically are at their worst in the morning. What helps for most people: taking medication at bedtime, says Richard Martin, MD, at National Jewish Health in Denver.
Go for walks in the evening
Not only do many people with allergies experience more sneezing and itching in the morning, but many trees release their pollen at first light, and ragweed pollen tends to fly most thickly at midday—so stick to nighttime strolls.
Put down your fork at least three hours before bedtime
In gastroesophageal reflux disease, also known as GERD, stomach acid frequently makes its way into the esophagus. This can cause or worsen asthma, experts say—even if you don’t experience symptoms of heartburn. Finishing dinner a few hours before bedtime can help.
5. Feel more energetic.
Sit by a window at breakfast
Morning exposure to bright light helps sync up your body clock to the world around you. This gets you ready for the day and helps you sleep at night.
Take a nap in the early afternoon
That familiar post-lunch fuzzy feeling doesn’t necessarily mean that you ate too much. You hit a biological soft spot in your alertness cycle in the early afternoon, so it’s a good time to snag a nap. You might feel even more refreshed if you drink a cup of tea or coffee before you lie down, suggests Jamie Zeitzer, PhD, a circadian biologist at Stanford University. That sounds counterintuitive, but the energizing effects of caffeine take about 45 minutes to kick in. (If you’re prone to insomnia, don’t nap after 5 p.m.)
Arrive in a new time zone early in the morning
That’s if you’re traveling east: Having the morning light on your face as you leave the airport can help reset your clock to the new time, Zeitzer says. If you’re traveling west, try to arrive in the evening. Zeitzer’s strategy for avoiding jet lag: For several days before you travel from west to east, seek strong light first thing in the morning to nudge your body clock forward. If you’re heading in the opposite direction, expose yourself to bright light in the evening for a few days before your trip to delay your internal sense that it’s bedtime. Whichever direction you’ve traveled, take a 3 mg dose of melatonin at bedtime on your first night in the new time zone, suggests researcher J. David Glass—it’s a sleep aid and another way to reset your internal timekeeper.
6. Time your refill right.
Some timing issues have nothing to do with biorhythms—but they still can have a major impact on your health. A 2005 study at the University of California, San Diego, showed a 25 percent jump in deaths related to medication errors in the first few days of the month. The possible explanation: Prescription refill requests pour in at the beginning of the month, after government checks arrive, which may overburden pharmacists. Always make sure that you’ve been given the right medication at the right dose.