There’s a reason most of us will get a burst of energy when we “spring forward” into longer days this month. It has to do with circadian rhythm—the internal, biological clock that helps our bodies know when to power up and power down.
For years, scientists and medical researchers understood that circadian rhythms had implications for jet lag, seasonal depression and shift workers, but the latest studies say the effects are much more wide-ranging. And these discoveries are so crucial to whole-body health that the American scientists behind them—Jeffrey C. Hall, Michael Rosbash and Michael W. Young—were awarded a Nobel Prize in 2017.
“Most of the chronic diseases we deal with today—diabetes, cardiovascular disease, digestive disorders, depression and more—can be prevented, managed or even cured by adhering to a lifestyle that’s in sync with the body’s circadian rhythms,” says Satchin Panda, PhD, author of The Circadian Code: Lose Weight, Supercharge Your Energy, and Transform Your Health from Morning to Midnight, and a professor at the Salk Institute For Biological Studies in La Jolla, California. Put simply: Live according to your circadian rhythms and you have a much better chance of boosting your energy, hitting your weight-loss goals and improving your all-around health.
Here’s where to start:
Table of Contents
When to Eat
Research published in the journal Cell Metabolism by Panda and colleagues found that eating all your calories within a 10-hour period each day prevented obesity and metabolic syndrome, a cluster of conditions including hypertension and high cholesterol that can increase your risk of diabetes and heart disease.
If you’ve heard of the popular diet trend of intermittent fasting, this is it. “It’s something so simple you can do,” Panda says. Delay your first meal of the day until about 10 a.m. (black coffee is fine), then stop eating by 8 p.m. In studies, animals who ate right up until bedtime showed signs of disease; the ones who were allowed food only within a 10-hour time frame did not, even though they ate the same diet.
When to Exercise
Because so few people exercise regularly, popular wisdom is that the best time to exercise is whenever you’ll do it. That’s true, but if your schedule is flexible, there is an optimal time. Factors like muscle flexibility and strength peak in the late afternoon (think 4-6 p.m.). “This means you’ll get the most benefit from exercise at this time, and you’ll be less prone to injury,” Panda says.
Training for a race or competitive event? Research published in the journal Sleepin 2013 indicated that professional football players playing close to their athletic circadian peak had a significant advantage over those who played at other times. The researchers followed NFL teams as they traveled across time zones and concluded circadian physiology had “profound effects” on human function.
When to Sleep
Humans are healthiest with plenty of light in the daytime and not much in the evening, says David K. Welsh, MD, PhD, associate director of the University of California San Diego Center for Circadian Biology. “Right now we have an epidemic of ‘social jet lag,’” says Welsh. “People are trying to live according to the schedule of their work and social lives. But this isn’t the same as what their biology dictates.” Our biology wants nothing to do with alarm clocks, late-night movies or staying up to all hours browsing Facebook. Welsh says for proper sleep and health, keep lights as dim as possible after sundown and avoid screens—especially blue-light emitting devices that we tend to look at close up. And get to bed in time to have at least 7 to 8 hours of shut-eye.