BALTIMORE — There’s no clock in baseball, but teams may do better or worse depending on the timing of their biological clocks.

Teams better acclimated to the time zone they are playing in have a circadian advantage over teams that are not yet used to the time zone, researchers in Virginia report. Examination of a decade’s worth of major league games shows that teams with this circadian advantage won 52 percent of the time. Those results were presented Tuesday, June 10 in Baltimore at SLEEP 2008, the annual meeting of the Associated Professional Sleep Societies.

The outcome of only a few games is affected each season, but “even if it’s small, small makes a difference,” at the level of professional and elite sports, says Cheri Mah, a researcher at the Stanford University Sleep Disorders Clinic and Research Laboratory. Mah was not involved in the study but has worked with athletes to see how sleep affects their performance.

“Every year there’s one team that misses the playoffs by one game,” says W. Christopher Winter of Martha Jefferson Hospital’s Sleep Medicine Center in Charlottesville, who led the study. “When the stakes are that high, this small advantage gets magnified. If this were any other industry, it probably wouldn’t matter.”

Winter and his colleagues tracked each team as it moved around the country for games and determined each team’s circadian state (acclimation to a time zone), and then the researchers matched that data with wins and losses.

When a team moves across a time zone, it takes a day to get used to the new time zone. So if the Los Angeles Dodgers travel from the West Coast to the East Coast to play the New York Mets, the Dodgers will be at a three-hour circadian disadvantage on the first day because they crossed three time zones. On the second day, the Dodgers will be at a two-hour disadvantage. If the team stays on the East Coast for four days or more — for instance, playing a four-game series with the Mets or going to Atlanta to play the Braves — it will be acclimated to the new time zone.

Of the 24,121 games played in the 10-year period from 1997 to 2006, 19,075 were between teams acclimated to the same time zone, so neither had a circadian advantage. In 5,046 games, one team had a circadian advantage. Of those games, 2,621 (51.9 percent) were won by teams with the circadian advantage.

The magnitude of the advantage matters. Teams with a one- or two-hour advantage won 51.7 percent of the time, but teams with a three-hour advantage won 60.2 percent of the time.

Rarely, visiting teams might have a circadian advantage over the home team; for instance, if the Dodgers have been on the East Coast for four days or more and then played the Marlins in Florida, while the Marlins had just returned home from playing the Colorado Rockies, then the Dodgers would have a two-hour circadian advantage. In those instances, circadian advantage took a back seat to home field advantage. Visiting teams with a circadian advantage won 619 games (45.3 percent) and lost 746 games.

In 2004, Winter and his colleagues found that teams that traveled from the eastern time zones to play in more western time zones had an advantage, winning 58 percent of their games. But the new study showed that over 10 years, the advantage actually goes to teams traveling east.

Winter says eliminating games in which one team holds a three-hour circadian advantage (about 16 games each season) would erase the bulk of the difference, but he’s not sure the major leagues will bother adjusting schedules for this small number of games.

“The baseball teams may not be as interested in these results as the bookies are,” he says.

In research reported June 9 at the sleep meeting, Mah also found that swimmers who slept for 10 hours a day for six to seven weeks shaved 0.51 seconds off their 15-meter sprint time, were faster off the blocks and in turns, and generally reported feeling more energetic and more focused.

It is harder to assess how altered sleep schedules might affect teams, but “when you’re at that professional level everything matters,” Mah says.

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