If you follow sports as closely as I do, you will be excited about some recent findings in my own fields of sleep and chronobiology. This data has been around for at least a decade, but it hasn’t been picked up by media outlets until recently. The bottom line is that West Coast teams of any sport have a significant performance advantage during night games, whether played at home or away.

ResearchBlogging.orgI chose to present the study that broke the ice in this week’s journal club since this upcoming weekend is Super Bowl Sunday. While I will not be enjoying the Super Bowl as much as I did last year because I actually went to it with a group of friends after we rented an RV and drove through the night (and back) to New Orleans, I don’t think this current study will carry much weight in this year’s Super Bowl since neither team is from the East Coast.

Super Bowl 2013

To begin, a team of sleep researchers at Stanford, which is the founding site of research in sleep medicine, tallied the number of games won or lost by a West Coast vs. East Coast team in an early vs. mid-afternoon vs. night game across 40 years of the NFL. As background, there is a disproportionate number of teams on the East Coast–17 in total– vs. the West Coast, 4 in total. This ratio of teams on the East vs. West Coast holds true for other professional leagues such as the MLB and NBA as well.

However, tallying the win-loss records of West vs. East Coast teams across 40 years of play in the NFL isn’t enough unanimous evidence to conclude that being from the West Coast presents a performance advantage. Many of these wins could manifest from a one-play fluke rather than an entire quarter or quarters of poorer performance. To control for this, the researchers factored in the Las Vegas point spread which is a fairly accurate measure of a team’s probability of winning (or losing). It is not solely based on a team’s current standings. It is a multivariate datum based on current line-up, the weather, how the current lineup historically adapts to the weather, whether it is a home or away game, injury reports, how a team’s offense and defense historically  plays against the opposing team, and on gambling behavior to an extent. These are just a few of many variables.

Using the Vegas point spread, a “win” in this study was defined by 1) actually winning the game and 2) additionally beating the point spread. For example, if the 49ers beat the Giants by “3,” but the point spread predicted a win by “6,” then the 49ers did not “win” under the study’s criteria. Seems qualitative enough, right? After re-computing win-loss records of West vs. East Coast teams under this criteria, a clear difference in the number of games won by a West vs. East Coast team emerged: over 70% of night games were won by West Coast teams. During the early and mid-afternoon, it was very much a 50-50 toss-up. Similar results were obtained in 1999 by Worthen et al. after analysis of the 1996 NCAA football season (the Florida Gators won that year).

To conclude, this is a beautifully constructed study. While mechanism may be lacking and would be confounding even if  core body temperature was measured to have a biomarker of circadian rhythmicity, we can postulate that the biologically clock is responsible. When East Coast teams play at night on the West Coast, the game is beginning at 11 pm EST and finishing around 2 am. If you have ever done a night race or have played an intramural game this late, you are very familiar with intermittent bouts of sleepiness in between intermittent bouts of adrenaline rushes. It sucks. In contrast, it is still a lot later for East Coast teams playing night games at home than it is for West Coast teams, at least biologically.

I wonder if this scientific evidence is also factored into the Vegas point spread. Hopefully so. It certainly doesn’t explain the losing streak of the Cleveland Browns that spans nearly two decades (because they are rarely invited to play games on prime time television), but it certainly enhances the reputation of  and respect for Tom “The Golden Boy” Brady and Belichick’s army of Patriots.

Smith RS, Efron B, Mah CD, & Malhotra A (2013). The impact of circadian misalignment on athletic performance in professional football players. Sleep, 36 (12), 1999-2001 PMID: 24293776

Worthen, J. B. and Wasde, C. E. (1999).
Direction of travel and visiting team athletic performance: support for a circadian dysrhythmia hypothesis Journal of Sport Behavior, 22 (2), 279-287