A new study has found that jet lag suffered by traveling long distances east or west can significantly decrease Major League Baseball players' performance in areas such as base running and pitching. According to the Science website, previous studies, such as one conducted in 2009, indicated that jet lag adversely impacted a team's chances of winning. However, none of those studies specifically found data on which aspect of an athlete's play were affected.
Study author Ravi Allada, a neurobiologist at Northwestern University, examined MLB data on players from 1992 to 2011, focusing on 4,919 games in which players traveled two to three time zones. He looked at certain statistics and analyzed whether players were more affected if they'd traveled east or west. Allada found that players traveling east were more affected and tended to play less aggressively, even if they were the home team.
“One of the more surprising things we found was that in some cases we would see effects on home teams and not away teams,” Allada said. “We don’t typically think of home teams as suffering jet lag, but that’s what we observed.”
Aaron Lee, a sports medicine physician for MacNeal Hospital in Chicago, Ill., who had previously studied the effects of jet lag in athletes in 2012, said the new study found evidence that because jet lagged athletes have impaired fine motor skills and cognition, their opponents are more likely to get home runs against them.
“Teams expect there to be a problem when they travel on the road, but I don't think anybody really thinks about the problems that could occur when they return home,” Lee said.
Colin Robertson, a United Kingdom chronobiologist in the University of Bolton's sports sciences department who did not participate in the study, said that unlike in many lab-based experiments, it was impossible to control differences between various players and teams, such as how much rest each player got or when each team's games were scheduled.
"Retrospective studies are a challenge from the outset because all the factors that are controlled for in a lab setting that we’re so fastidious about are lacking,” Robertson said. “This [study] was really ambitious.”