By Michael Breus, PhD, ABSM
Whether you’re a fierce competitor in your fantasy football league, or you’d just like to be on the winning end of the couch come game day, here’s a tip that could help you pick your team: when making your prediction, consider circadian timing.
This advice may seem far afield from rushing yards, completion percentages, power rankings, or any of the other typical criteria fans consider when assessing a team’s prospects on game day. But you’d be surprised how relevant circadian timing—and sleep more broadly—can be to a team’s success. New research indicates that the timing of play in relation to players’ circadian rhythms is a factor in NFL team performance. Scientists at Harvard, Stanford, and the University of California San Diego analyzed 40 years of NFL games between East Coast and West Coast teams, and found that West Coast teams appear to have a distinct advantage over their East Coast competitors when competing in games that start after 8 p.m. Eastern Standard Time. Researchers identified 106 games between 1970 and 2011 that included East Coast-West Coast match ups where kickoff occurred after 8 p.m. EST. They used 293 games played by the same team match ups during daytime hours as a control group. In analyzing their data, researchers controlled for other factors that could influence the outcomes of games. In particular, they used the Las Vegas point spread to factor out other game-day influences, including team skill differences, home field advantage, and player injuries. After adjusting for the point spread, West Coast teams demonstrated a clear advantage in evening games against East Coast teams:
- West Coast teams beat the point spread twice as often as East Coast teams in games played after 8 p.m. EST.
- West Coast teams beat the point spread in 66% of the games, by an average of 5.26 points.
- In contrast, there was no advantage for West Coast teams over East Coast teams in games played during eastern standard daytime hours.
This new study follows up on earlier research conducted by some of the same scientists. That study examined East Coast-West Coast NFL Monday Night Football match ups that started after 9 p.m., during the years 1970 to 1994. That analysis also found that West Coast teams significantly outperformed the point spread in evening games against East Coast teams. The advantage was significant enough to eliminate home field advantage for East Coast teams playing at night, in the researchers’ estimation. Studies of other professional league play have also returned similar findings. An analysis of circadian timing as a factor in Major League Baseball found that West Coast teams traveling east to play were more likely to prevail in games than East Coast teams traveling west.
So what’s at play in these results? How does circadian timing translate into such a clear performance advantage? The body’s circadian rhythms control a range of important physiological process, including sleep and activity levels, on a 24-hour cycle. All of us—professional athletes, weekend golfers, and couch surfers included—experience optimal and preferred times for rest and for different types of activity, based on our individual circadian clocks. When the timing of an activity is in line with circadian rhythms, our performance at that endeavor is likely to be closer to its best. (Mid-morning, for example, is a time that’s often associated with peak cognitive function, which is why you may often feel you hit a groove at work during these hours, before a commonly experienced mid-afternoon slump.) For professional and competitive athletes, this means that taking the field at the right time of day can give them an edge over players who are gearing up to perform at different, less conducive points in their circadian cycles.
Forget what the wall clock says—when it comes to the benefits of circadian timing to athletic performance, it’s the body clock that matters. West Coast teams playing during evening hours on the East Coast have an advantage of playing in their biological, circadian late afternoon—considered to be an ideal time for physical and athletic performance. Research indicates that several aspects of athletic performance peak during the late afternoon and early evening, when body temperature nears its highest daily levels. For athletes this time of day is when strength, speed, flexibility, and endurance are often at their overall best—and risk of is injury at its lowest.
Of course, circadian timing isn’t the only sleep-related factor that can contribute to—or undermine—success in sports. Athletes face any number of sleep challenges, including grueling practice and game schedules that don’t allow for sufficient rest, sleep and performance hazards associated with frequent travel and jet lag, and the sleep-disrupting anxiety of performing at an elite level. Research demonstrates that extending sleep times and allowing for the creation of healthy sleep routines for athletes enhances both their physical performance and their mental game, as well. And professional sports seem to be slowly waking up to the power of sleep to improve athlete performance, protect athletes’ health, and even to extend career duration.
While you may feel you don’t share much in common with a professional linebacker, when it comes to circadian timing we’re all influenced in similar ways, which means the success, ease, and pleasure of daily activities can often be affected by their alignment—or lack thereof—with circadian rhythms. I’d like to see greater attention paid not only to the importance of circadian timing in professional and elite sports, but more broadly to how we all can benefit from better aligning our lives, including our work and school schedules, with circadian timing in mind.
Michael J. Breus, PhD
The Sleep Doctor™