Getting out of bed in the morning, especially in the persistent darkness this time of year, can be tough sledding. But when it comes to athletics it might be worthwhile to pay heed to the alarm clock—at least for some players.
So says a new study that suggests our individual internal clocks hold significant sway over athletic performance. The new study categorizes athletes as either morning people (“larks”), evening people (“owls”) or somewhere in-between, and takes stock of how athletes perform in endurance testing throughout the day. Surprisingly, it finds that there is more difference in athletic performance around internal chronology than was previously thought. For an evening person, athletic performances can differ by as much as 26 percent in the course of just one day, making for lackluster achievement in the morning, according to these findings.
The work is certainly not the first to put forward the idea that there are natural fluctuations in physical and cognitive performance that track with natural daily biological patterns in humans called circadian rhythms. But these new findings, published in Current Biology, suggest athletic performances can differ by enormous margins at certain times of day and that there are consistent peak performance times for early- and late-risers, which hinge on time since awakening. The study suggests that a late-riser competing in an evening event like the Super Bowl may be at an inherent advantage because that timing aligns with his expected peak performance. Although competition schedules cannot often be controlled by players, coaches and athletes can also adjust training times to make sessions most efficient, says the new study. To date, the biggest circadian upsets for pro athletes has likely been traveling between coasts and dealing with different time zones. But this new work suggests that perhaps more training should be put into adapting average daytime routines, too.
To pin down individualized internal clock data, researchers from the University of Birmingham (U.B.) in England crafted a specialized questionnaire that clarifies when athletes perform best. To that end, the researchers asked 121 competition-level athletes questions about wake-up times, sleep-onset times, sleep duration, light exposure, daily schedules and other information. Then, they asked 20 of those athletes—all regional club or international-level field hockey players—to commit to several athletic performance tests during the day (which were compared with their circadian rhythm data) and complete a longitudinal sleep/wake diary to check daily routines. The researchers followed up with similar testing of 22 (mostly male) squash players from the U.B. squash team to verify their findings. On average, among the night owl group the researchers found athletic performance can vary greatly. Yet for earlier risers the differences were consistently in the range of 7 to 10 percent. Some of that discrepancy may be due to intrinsic features in late-risers, such as diminished levels of a hormone vital for muscle function called cortisol, the authors wrote.
When it comes to optimal athletic performance, the endurance reports suggest that early-rising athletes should compete about six hours after they wake up. For late-risers, however, it gets trickier: peak performance comes 11 hours after rising. So if an early-riser has a set wake-up time of 7 A.M. then that person will probably perform their personal best around 1 P.M. For that same person competing in the evening, however, it would be more challenging because her circadian system would already be approaching the end of her biological day, wrote lead author Roland Brandstaetter via e-mail. Meanwhile if a person has a normal wake-up time of 11 A.M.—suggesting she is from the latest-rising “owl” circadian rhythm group—then her peak performance will typically be around 10 P.M.
Due to that late peak, “I would look at this and say if you are an evening person, you are at a disadvantage in exercise performance—except if you play Monday night football,” says Steven Feinsilver, director of the Center for Sleep Medicine at Mount Sinai Hospital in New York City. Most college athletic and Olympic events are daytime activities. Still, it wouldn’t be advisable for such night owls to awaken at 4 A.M. to prepare for early afternoon games because that would eventually lead to sleep deprivation and hinder athletic performance, warns Feinsilver, who was not involved with this study.
In the long run there is no need to fret if an owl has an early-afternoon kickoff time, according to Brandstaetter. Individuals can and do alter their internal clocks. And within a certain range the body clock can be reset to a certain schedule—but it is not easy. Humans can naturally change their body clocks about an hour a day at most, so it would take awhile to shift the bodily cycles, Feinsilver says. Future work may look at what happens when owl athletes are forced into morning schedules. For now, among most casual athletes, the variability in athletic performance would not be a big deal. But for Olympic-level athletes, it may be time to put more stock into considering how many hours after wake-up time players do best. A 1 percent difference, the authors wrote, could be the difference between a gold medal and no medal at all.