How to Use Your Body Clock to Beat Jet Lag, Stop Late-Night Snacking, and More
What's your body clock, anyway?
Your body runs on circadian rhythms—patterns in biological processes that repeat every day. And those cadences are controlled by an internal clock.
Where is the body's clock? In the part of the brain called the hypothalamus, above where the optic nerves cross, is a group of about 20,000 nerve cells known as the suprachiasmatic nucleus (SCN). Influenced by light, it controls your body’s production of the sleep-inducing hormone melatonin. When light levels are low, like at night, the SCN tells your brain to churn out melatonin, which makes you sleepy.
"The tick and tock of your body clock can really affect your health,” says Michael Smolensky, PhD, cofounder and former director of the Memorial Hermann Chronobiology Center at the University of Texas. Follow these tips for keeping your cycles in sync so you can feel better, boost your immunity, sleep more deeply, and more.
Camping can reset your body clock
Do you struggle to doze off at a decent hour? The solution may be as simple as pitching a tent. When University of Colorado Boulder researchers sent people camping for a weekend, they found that after the participants returned to civilization, their evening rise in melatonin levels had shifted 1.4 hours earlier, and they went to sleep and woke up earlier than those who had stayed home.
“When you take away artificial light—which is what happens when you go out into the wilderness—we see melatonin revert to its natural pattern,” says Michael Breus, PhD, a sleep specialist and the author of The Power of When ($15; ). Can’t tolerate a tent, even for a weekend? Breus suggests dimming the lights in your home and shutting off all electronics 60 to 90 minutes before bed.
Your daily routine can make a difference
This routine would work for most folks with typical sleep-wake schedules.
6 A.M. Go for a run. Assuming you’re healthy overall (especially cardio-wise), your low body temp makes the morning good for endurance sports like jogging.
8 A.M. Prep for a pitch. “Studies suggest this is when you have the best immediate recall,” says Smolensky.
2 P.M. Take a quick nap. Your alertness dips now. Just keep your power nap short—20 minutes tops.
5 P.M. Meet a pal for tennis. Your hand-eye coordination is at its highest in the early evening.
6:30 P.M. Eat dinner. Dine at least four hours before bed for better digestion and to lower your chance of heartburn.
9 P.M. Relax in a hot bath. It triggers a rise and fall in body temp that helps you nod off faster; shoot for one hour before bed.
How to beat jet lag
Jet lag is always a pain—but you may feel worse when you travel from west to east. That’s because the body clock is actually slightly longer than 24 hours, says neurologist Alon Avidan, MD, director of the UCLA Sleep Disorders Center: “It’s only about 30 minutes longer, but it means it’s easier to go west and lengthen your day, versus flying east and shortening it.” If you’re headed east, start moving your bedtime back about a half hour each night for several nights. When you land, resist the urge to head to your hotel and nap. “You want to get as much natural light as possible,” says Dr. Avidan. Then, at about 9 p.m., take a 0.5-milligram dose of melatonin. Do that for the next few nights, depending on how many time zones you’ve crossed. (A good rule of thumb: one night for every time zone.)
Midnight munching can disrupt your body clock
Late-night snacking may come back to haunt you. Food signals to the body that it’s time to be awake—making it tougher for you to nod off and get a full night’s sleep, says Andrew W. Varga, MD, assistant professor of sleep medicine at the Icahn School of Medicine at Mount Sinai in New York City. At the same time, your circadian rhythms affect how you metabolize food: “Eating late at night leads to a bigger blood sugar spike,” says Dr. Varga, “and fats are more likely to be stored as fat in the body, causing weight gain.”
Forget early birds and night owls
Breus argues that most of us fit into one of four chronotypes.
If you’re a lion… You’re an early riser who’s prone to a midafternoon slump and feels wiped out by early evening. The trick to extending your day? Work out in the p.m. for an energy boost, says Breus.
If you’re a bear… Your focus is highest between 10 a.m. and noon. You should tackle big projects in the morning and save your socializing for early evening, when your mood peaks.
If you’re a wolf… Try to schedule meetings when you’re most alert, between 4 p.m. and 6 p.m. If you need to be up early, Breus suggests taking a walk outside first thing in the morning.
If you’re a dolphin… You’re familiar with the wee hours. But no matter how little sleep you get the night before, try to exercise in the morning to kick up your energy level. And remember to nix electronics after 10:30 p.m.
Your immunity peaks in the morning
Make a note: When you get your flu shot this fall, go early in the day. In a U.K. study published last year, researchers looked at 276 senior citizens and found that those who got the vaccine between 9 a.m. and 11 a.m. had a higher antibody response to two out of three flu strains one month later than those who got their shot between 3 p.m. and 5 p.m.
“Immune cell numbers and sensitivity to pathogens fluctuate over the course of the day,” says Adam Silver, PhD, assistant professor of biology at the University of Hartford in Connecticut. “It’s believed that our immune system evolved to be at its peak when we are most likely to encounter pathogens, so it makes sense we’d see a heightened immune response in the morning, at the beginning of our active period.”
Plus, your arms will thank you: Smolensky’s research has shown that people who get vaccinations early in the day are less likely to experience redness, soreness, or hardness at the injection site.
Could you have a circadian rhythm disorder?
If you struggle to drag yourself out of bed in the a.m. or stay awake past dinner, you may be suffering from one of these.
Delayed Sleep Phase Disorder: People with DSPD tend to fall asleep anywhere from three to six hours after a “normal” bedtime, which makes it challenging to rise and shine.
Treatment: Bright blue light therapy in the morning, avoidance of blue light in the evening (particularly from backlit screens), and a low dose of melatonin (0.5 to 1 milligram) three to four hours before a desired bedtime usually helps, says Dr. Varga.
Advanced Sleep Phase Disorder: This condition involves falling asleep several hours earlier than most people—and feeling wide awake before sunrise. ASPD occurs in about 1 percent of middle-aged adults and becomes more common as people age.
Treatment: Bright blue light therapy in the early evening can reset your circadian rhythms and help delay sleep onset, explains Dr. Varga. You can also try gradually shifting your bedtime—for example, pushing it 15 minutes later every two or three nights.
Why shift work can be risky
“Your circadian rhythms affect how your body functions on a cellular level,” explains Dr. Avidan. “When they’re disrupted, levels of hormones that impact your risk for heart disease, obesity, even your immune system are all affected.” But if your workday begins after sunset, there are a few ways you can help your body clock stay on track. Dr. Avidan recommends getting as much light exposure as you can while at work. After you clock out, do your best to limit your light exposure; once you get home, try using blackout curtains to help you sleep.