In the human brain, the hypothalamus houses a small region called the suprachiasmatic nuclei, which is responsible for our circadian rhythms. Our most notable circadian rhythm is our sleep-wake cycle, but there are also less obvious ones. Perhaps one of the most influential is our alteration of arousal throughout the day. When we are most lively (it peaks in the morning and early evening), physical and mental performance is at its highest. Conversely, they are at their lowest when you get closer to midnight.
Previous studies have shown us that our peak athletic performance is in the late afternoon, and athlete’s subjective reports corroborate these findings. Given this, it would make sense then that Monday Night Football games in the NFL do not facilitate peak performance, since our rhythms are continuously dipping during this time of the night. This may be true, but is it for every team?
Sleep scientists at Stanford answered this question with a retrospective study of Monday Night Games over a 25 year period. They hypothesized that west coast football teams would have an innate advantage over east coast teams when playing in the east coast (e.g. the San Francisco 49’s playing at the Detroit Lions). This prediction was based solely on circadian preferences. On Monday Night Football games being played on the east coast, both teams are playing at 9:00pm, but the west coast team is essentially playing at 6:00pm, which is very close to the time of day that allows peak performance.
Amazingly, this is exactly what they found; west coast teams won more often and by more points per game than the east coast teams. Over this 25 year period, west coast teams won 59.3% of their home games, and 71% of Monday Night Football home games. East coast teams won 56.5% of their home games, but only 48.3% of their Monday Night Football home games. When an east coast team plays a team in any other time zone, their win percentage jumps up to 67.5%. Similarly, when a west coast team plays a non-east coast team, their winning percentage drops to 58.1%. These numbers tell us that when a west coast team plays on Monday night versus an east coast team, whether it be home or away, their circadian rhythm gives them a strong advantage.
What makes this finding even more incredible is that these analyses took the point spread into account, which thwarts the argument that west coast teams just might be better than east coast teams (the point spread is a metric which includes a number of factors that would place one team at an advantage over the other: skill, injuries, etc.).
Since this study, NFL teams have taken their circadian rhythms into serious consideration when preparing for their next game; teams will often hire sleep specialists to coordinate travel plans for away games. In my own personal opinion, this is one of the main reasons why there will never be a permanent NFL team in London. It would offer a distinct home field advantage for the London team, and will confer a serious disadvantage for away games due to their constant travel across the pond. If the NFL wants an team in London, they must take their player’s biological rhythms into consideration.
Smith, R. S., Guilleminault, C., & Efron, B. (1997). Sports, sleep, and Circadian rhythms Orcadian rhythms and enhanced athletic performance in the National football league. Sleep, 20(5), 362-365.