In baseball, do home teams have a better chance of winning in their home ballpark? Bookmakers have always given better odds to the home team, for a variety of reasons. It’s a given that the home crowd roots for home team players, but clearly the visiting team is usually presumed to be “more tired” because they’ve often traveled from another time zone or journeyed for some hours. But what if there is another twist to these variables? Consider if the home team just returned from a road trip in a different time zone, while the visiting team arrives to play in the same time zone?
Things just got a bit more complicated.
Relatively new scientific data takes all these variables and scenarios into account and measures impact and outcome on baseball player and team performance for a given game. This extensive study was published in the Proceedings of the National Academy of Science of the United States of America National Academy of Science in December, 2016. It reinforces how crucial adequate sleep and timing of sleep is.
The study analyzed the performance of 46,000 Major League Baseball (MLB) players, over the course of 20 years, between 1992 and 2011. Researchers analyzed performance relationship to many other factors besides “travel through time zones.” They found that the advantage of playing on one’s home field disappeared when the home team traveled through time zones, back home, and then immediately played a visiting team playing in their same time zone.
The negative impact on the home team was noted to be more pronounced with travel eastward (to return home).
Taking jet leg into account
The effects of this type of pre-game travel on the home team are somewhat subtle. When assessing the influence of jet lag, and specific direction of travel on player performance, the measure was not just which team won more games but also an analysis of the performance of individual player positions.
Pitchers, for example, gave up more home runs when they (presumably) had jet lag. A pitcher, thanks to adrenalin and his position, may start the game awake and strong (despite jet lag), but all it takes is loss of concentration on one pitch (jet lag raises the risk) to allow a base-scoring hit or home run from the opposing team’s batter. That moment can change the trajectory of the game, and “presumed” home team advantage.
A similar pattern was observed in batter performance. Players who traveled home, by flying east, hit fewer balls overall, had fewer doubles, and stole fewer bases. The traveling visiting teams may also follow stricter schedules (to make up for the fact that they are traveling), which could help them recover faster from jet lag, while the home team may also have additional responsibilities and obligations that interfere with the adjustment when they return home.
Some team managers have been clued in to these realities long ago, simply by careful observation, and often have the “starting pitchers” travel to the location where they will be pitching one day earlier than the rest of the team, just to acclimate.
Eastward? Westward? There's a difference
Eastward or westward air travel across time zones can precipitate both transient insomnia and hyper-somnolence. When jet lag does occur, the person’s intrinsic circadian rhythm remains temporarily aligned to the home time zone and has not yet synchronized to the external cues in the new local time zone.
Individuals traveling westward are phase-advanced, relative to the new local time zone, while those traveling eastward are phase-delayed. This means that one’s body clock is ahead of (phase-delayed) or behind (phase-advanced) the local time zone.
The observations from this study can be applied not only to other professional sports, but also to other professions that involve travel. That includes individuals in the military, pilots, and business people.
A westward flight is associated with early evening sleepiness as well as an increase in wakefulness during the early morning hours. Conversely, eastward flights result in difficulty falling asleep and difficulty awakening the next day.
Symptoms are generally more pronounced with eastward travel that entails a phase advance. Prior sleep deprivation (before travel), and factors associated with travel like psychological stress and prolonged inactivity during flights, may also influence symptom severity.
Adjustment is characteristically more difficult following eastward travel which requires advancing the circadian phase.
Check out my earlier column on traveling through time zones to learn tips on how to prepare for travel east or west and the measures to take in the days leading up to travel.
Jet lag is one instance where melatonin supplementation helps the most. The critical factor is the time when melatonin is taken. Remember that adjusting one’s schedule in preparation for being in the new time zone doesn’t only require sleep and wake time adjustments, but also adjustments to eating and exercise times.
Baseball players or not, we are an increasingly mobile society, and more is expected from us whatever our profession. Understanding the rhythm of our circadian clock in relation to, the ever-changing “time” environment, especially when we travel, is critical to optimal performance.
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Eli Hendel, M.D., is a board-certified internist/pulmonary specialist with board certification in Sleep Medicine. An Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, and Qualified Medical Examiner for the State of California Department of Industrial Relations, his areas include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases. Favorite hobby? Playing jazz music. Find him on Twitter @Lung_doctor.