If you travel, work late, stare at a smartphone or occasionally drink into the night—essentially, if you live a typical modern life—then your circadian rhythm is very likely out of whack. The light-dark cycle affects your metabolism—and nearly everything else. Below, some vital tips on exercise, snacking, and travel.
The 24-hour schedule by which your body induces you to sleep, signals you to wake, urges you to eat, releases hormones, shifts your internal temperature and maintains other processes is essential to well-being. These physiological changes are determined by "clocks" found in your brain and in cells throughout the body, which stay in tune—or become discombobulated—as a result of light and dark cues from your environment and lifestyle.
"If you think of the body as an orchestra, with the brain as the conductor, everything has to be in perfect sync," says Paolo Sassone-Corsi, Ph.D., Director of the Center for Epigenetics and Metabolism at the University of California, Irvine School of Medicine and a leading expert on circadian rhythm. "When we eat or sleep at the wrong time, we're imposing stress, and that's not good."
One key factor affected by the sun-moon cycle? The health of your metabolism. A 2012 study by Sassone-Corsi found that an impressive 60 percent of metabolites, chemicals that maintain proper cell growth in the digestive system, are dependent on a light-dark cycle to function. Overall, 15 percent of the genes in your body's cells are subject to a 24-hour cycle, and a huge body of research has linked day-night disruption to insulin resistance and obesity, diabetes, heart disease, cancer, depression and even increased susceptibility to intestinal infections like salmonella.
Correcting your sleep-wake-eat pattern decreases the likelihood you'll experience these problems. We found three easy, everyday ways to maintain a healthy hum.
Exercise in the afternoon
According to a 2012 UCLA study on mice, regular workouts may increase the brain's production of proteins that get distributed to crucial organs like the heart and liver, helping them stay on the correct day-night rhythm and operate properly. Mice that exercised late at night (the human equivalent of midday) showed the biggest improvement in circadian rhythm.
Ditch the midnight snack
We've all done it, but the late-night calorie explosion is a real ticking time bomb for your health. "Metabolic cycles need to be active to receive food," Sassone-Corsi says. In experiments on mice, those that consume a high-fat diet during the day can stay lean; it's the night calories that make them fat.
Changing time zones puts major stress on circadian rhythm—in fact, epidemiological studies have found higher disease rates among flight attendants. In the days leading up to a trip, try going to bed and waking up earlier (or later) in anticipation of the shift. Once you arrive, spending time in the sun and immediately enforcing a healthy bedtime (10pm) should help your rhythm adjust quickly, according to the National Sleep Foundation.