Super Bowl outcome depends on players' biological clocks, study suggests

America's biggest game this weekend has sports fans agonizing over which team will take home the title of Super Bowl champion. One new study suggests the deciding factor has nothing to do with the hype, but how the timing of the game aligns with the internal biological clocks of the athletes.

Researchers from the University of Birmingham in the UK analyzed the circadian phenotypes of more that 120 athletes, determining if they were classified as early (larks), intermediate, or late (owls). Then they completed fitness tests at six different times of day.

Circadian phenotypes were determined using a survey method called the RBUB chronometric test which collects information on wake-up and sleep-onset times, sleep-onset delays, sleep duration, alarm use, light exposure, food intake, work schedules, sleep quality, daytime naps, periods of mental and physical high and low activity, energy drink consumption, alcohol consumption, caffeine consumption and smoking.

The study found that the performance of competition-level athletes varies over the course of the day by as much as 26 percent. People who would naturally prefer to sleep in will give their best performances hours later in the day than early birds will.

Dr. Roland Brandstaetter, study author and researcher at the University of Birmingham told that his team was surprised at just how much impact an individual's body clock had on performance.

"If a one percent difference in performance can make the difference between first place and fourth place in a 100-meter race and actually win you the gold medal at the Olympics, then imagine what a 26 percent difference in your performance could give you," he said. "Our research takes us away from the idea of 'time of day of the race' and directs us more to internal biological time."

Brandstaetter said athletes and coaches should make note of the findings and adjust their schedules accordingly.

"It is extremely important for coaches to know when their athletes perform their personal best. A football coach with a team that consists of 50 percent early circadian phenotypes will do very well in afternoon matches but the team will terribly fail when they have to play in the evening," Brandstaetter said. "A team with many late types, however, will have an advantage. Coaches could choose from equally skilled players according to their circadian phenotype depending on when they have to play matches."

Brandstaetter said the findings may even mean performance tests among athletes are skewed, depending on what time of day they are conducted – begging the question of how many talented athletes have been passed on because they were tested at the wrong time for their biological clock.

The good news for athletes? Brandstaetter said it's possible to "re-train" your circadian rhythms by adjusting a variety of environmental clues, including light exposure, food consumption and activity. If applied in the right way and at the right time for the specific individual, circadian rhythms can be shifted – meaning an entire team could be on the same clock performing their best, come game time.

But the adjustment doesn't happen overnight, he warned. According to Brandstaetter just getting up at a certain time on the day of the competition will not help if that time is different from an athlete's internal biological time. To "shift" the body clock will take between three days and a week. depending on the individual.

"From the psychological side of things, allowing a coach to be able to understand their athlete's body clock and how it affects them could be hugely beneficial," he said. "Coaches would be able to recognize times when their athlete is not at their best and needs more encouragement, or even a strategic power nap."

Study results are published in the Cell Press journal Current Biology.