If you're an early riser, your peak performance is earlier in the day, typically around lunchtime. If you're a night owl who prefers to sleep in, your prime time is closer to 8pm. One's internal body clock, which influences everything from alertness to risk of heart attack, has such an impact on performance that it can vary by as much as 26% over the course of the day. Reporting in the journal Current Biology, researchers analyzed 20 female hockey players who were described as "larks", intermediate types, and "owls," and had them perform a series of sprints 6 times a day, reports Science 2.0.
The best predictor of how well they performed at a given time? How long it had been since they would have woken up in the morning if not relying on artificial means like alarm clocks. "Only by taking internal time into account can true and fair assessments of human performance become possible," one researcher tells the BBC. Talent spotters who observe adolescents—half of whom are night owls at that age—during school hours are "missing out on a huge number of high performers by testing at the wrong time of day," another doctor says. As for Sunday's Super Bowl, it's possible that one team could edge out another simply because more of its players are suited to the kickoff time. (Check out what butterflies teach us about our own biological clocks.)