According to research presented Tuesday at SLEEP 2008, it is more than just practice that gives certain Major League Baseball (MLB) teams an advantage.

During this study, scientists measured circadian advantage with the convention that with every time zone crossed, synchronization to the new time zone takes one day. Teams were given a daily number indicating the number of days they were away from being synchronized with the time zone they were playing in. A positive value was indicative of eastward travel, negative values were indicative of westward travel, and zero value was given to indicate synchronization with the current time zone.

Of the 24,133 games analyzed, 79.1% were played between teams at equal circadian times. Of the remaining 5,046 games, the team with the circadian advantage won 51.9% of the time. After the home field advantage was accounted for, the away team with the circadian advantage won 45.3% of the time.

“The magnitude of circadian advantage influenced success. When teams held a 1-hour circadian advantage, winning percentage was 0.517. When teams held a 3-hour circadian advantage, winning percentage increased to .603,” says W. Christopher Winter, MD of Martha Jefferson Hospital in Charlottesville, Va, lead author of the study.