Measuring circadian advantage in Major League Baseball: a 10-year retrospective study.
OBJECTIVE
The effect of travel on athletic performance has been investigated in previous studies. The purpose of this study was to investigate this effect on game outcome over 10 Major League Baseball (MLB) seasons.


METHODS
Using the convention that for every time zone crossed, synchronization requires 1 d, teams were assigned a daily number indicating the number of days away from circadian resynchronization. With these values, wins and losses for all games could be analyzed based on circadian values.


RESULTS
19,079 of the 24,121 games (79.1%) were played between teams at an equal circadian time. The remaining 5,042 games consisted of teams playing at different circadian times. The team with the circadian advantage won 2,620 games (52.0%, P = .005), a winning percentage that exceeded chance but was a smaller effect than home field advantage (53.7%, P < .0001). When teams held a 1-h circadian advantage, winning percentage was 51.7% (1,903-1,781). Winning percentage with a 2-h advantage was 51.8% (620-578) but increased to 60.6% (97-63) with a 3-h advantage (3-h advantage > 2-hadvantage = 1-h advantage, P = .036). Direction of advantage showed teams traveling from Western time zones to Eastern time zones were more likely to win (winning percentage = .530) than teams traveling from Eastern time zones to Western time zones (winning percentage = .509) with a winning odds 1.14 (P = .027).


CONCLUSIONS
These results suggest that in the same way home field advantage influences likelihood of success, so too does the magnitude and direction of circadian advantage. Teams with greater circadian advantage were more likely to win.
Winter
W Christopher
WC
Martha Jefferson Hospital Sleep Medicine Center, Charlottesville, VA. USA.
Hammond
William R
WR
Green
Noah H
NH
Zhang
Zhiyong
Z
Bliwise
Donald L
DL
D054874:Athletic Performance / Q000502:physiology*; D001484:Baseball / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D006801:Humans; D012189:Retrospective Studies; D013998:Time Perception / Q000502:physiology*; D014195:Travel; D014481:United States