Eastward Travel Harder on the Body Clock
A trip across two or three time zones can make ordinary people feel out of sorts, and even world-class athletes can lose their competitive edge.
A team of researchers who studied more than 46,000 Major League Baseball games over the 20 years between 1992 and 2011 found that player and team performance was measurably impaired by jet lag, which was defined a having had to travel over two or more time zones to get to a game.
Jet lag is a physiological condition in which the body's circadian rhythms are altered. Circadian rhythms, the body's internal clock, are the 24 hour cycles of physiological, biochemical and behavioral processes that drive a wide range of functions in humans and other living organisms. In their recent paper published by PNAS.org, scientists at Northwester University explained that when people fly across two or three time zones their internal 24-hour clock becomes misaligned with the natural environment and its cycle of light and dark. Teams that has crossed one time zone, and had to adjust to a time difference of only one hour, were not considered jet lagged.
Dr. Ravi Allada, the Edward C. Stuntz Distinguished Professor and chair of the Department of Neurobiology at Northwestern University, said in a university news release that the negative effects of jetlag are detectable and significant. Dr. Allada, an expert in circadian rhythms and the lead author of the study, said both offense and defense, in both home and away games, were impacted, and often in surprising ways. For example:
- The impact of jet lag impairment was stronger for those traveling east than for those traveling west. The authors say that findings supports the hypothesis that the impairments were caused more by failure of the circadian clock to synchronize to the environment light-dark cycles than to the general effects of travel.
- The offense of jet lagged home teams was more impacted than the offense of jet lagged away teams. Surprisingly, jet lag from eastward travel had a more negative impact on home teams returning from a road trip than it did on away teams.
- Negative impact on offense was related to running, and measured by fewer stolen bases, fewer doubles and tipples, and hitting into more double plays.
- Both home and away teams, when jet lagged, gave up more home runs. Jet lagged pitchers, especially when they had traveled east, gave up more hone runs.
Dr. Allada says if he were a team manager, he'd send his first starting pitcher to a distant game site a day or two ahead so his body clock could adjust to the local environment. Dr. Allada says the 2016 National League Championship Series offers a possible example of the impact of jet lag on player performance. In Game 2, LA Dodgers ace pitcher Clayton Kershaw shut out the Chicago Cubs, giving up only two hits. In Game 6, when the teams returned to Chicago from LA, the Cubs scored five runs, two of them home runs, off Kershaw. "While it is speculation," Dr. Allada said, "our research would suggest that jet lag was a contributing factor in Kershaw's performance."
The disruption of circadian rhythms has also been found to impact workers in other fields.