Jet Lag Does Not Decrease Collegiate Football Performance

It is commonly accepted that traveling across time zones affects sport performance via “jet lag,” but this is premised on lab-based studies and poor-quality evidence from analyses of real-world data from team sports. For example, Smith et al. primarily used t-tests to show that West Coast NFL teams were more likely than East Coast teams to beat the Vegas spread in evening games (non-coastal teams were omitted). No analyses of real-world data consider time zone change or game time as continuous constructs, nor do they account for important contextual information. PURPOSE: Analyze data from college football seasons 2013-2022 in a causal inference framework to determine if time zone changes and kickoff time decrease the likelihood of beating the Las Vegas betting spread. METHODS: The potential outcomes causal inference framework and a generalized additive mixed model (GAM) were used to nonparametrically assess the potential nonlinear impact of time zone changes on the away team beating the Las Vegas spread with an effect modification of kickoff time. Inverse probability weighting was used to orthogonalize the relationship of these “treatments” to the following variables: turf type, stadium type, precipitation, humidity, temperature, and wind speed. Since valid standard errors cannot be calculated from GAMs with weights, we used randomization inference to compare the interaction effect to a simulated null distribution. We simulated 5,000 datasets of random “treatments” under the positivity assumption. RESULTS: The real data were highly compatible with the null hypothesis of no effect for hours lost/gained in travel and game time (p = 0.471). The point estimates for the probability of beating the spread are in Figure 1. CONCLUSIONS: We must rigorously interrogate assumptions regarding what affects performance in team sports. There is no clear indication that jet lag and game time affect collegiate football performance when appropriate analyses are performed.