Effect of time zone and game time changes on team performance: National Football League.

To determine the effect of time zone and game time changes on NFL team performance, win-loss records from 1978-1987 were analyzed. Twenty-seven NFL teams were grouped by time zone and possible anti-jet lag adjustments. Among all intra-time zone rivals, home teams won 56.6%, away teams won 43.8%, for a home vs away winning percentage change of -12.8% (P < 0.001). West teams (N = 5) displayed fluctuations in home vs away team performance in association with trans-meridian travel. The change in winning percentage was found to be 0.0% vs West teams, -14.1% vs Central teams (N = 8) (P < 0.05), -16.3% vs East (N = 14) (P < 0.05) for West teams (N = 4) flying about 42 h pregame and +2.3% vs East for the one West team advancing practices 3-4 h to match East coast game time in addition to 48 h pregame flights. For night games within the same time zone, home vs away team winning percentage changed -23.8% (P < 0.01). West teams displayed uniformly high home winning percentages (75.0% and 68.4%) when playing Central and East teams, respectively, with little or no fall in away winning percentages (67.7% and 68.8%). For day games, a 3-h phase advance may decrease West coast team performance. In one small subset, anti-jet lag adjustments appeared to eliminate the expected decrement in performance. For night games, West coast teams, whether home or away, appear to be at a distinct advantage over East and Central teams.