Time Zones, Body Clocks, and the NFL: Why the Clock Quietly Picks Winners

On Sunday, October 25, the Pittsburgh Steelers and New Orleans Saints kick off at Stade de France at 2:30 p.m. Paris time. For the players' bodies, though, it will not feel like the middle of the afternoon. A Steeler whose body clock is still set to Pittsburgh will play at 9:30 in the morning, and a Saint still on New Orleans time at 8:30. A few hours before kickoff, every clock in France falls back one hour.

That is not trivia. Three decades of research on the NFL, MLB, and NBA point in the same direction: the time on a player's internal clock is part of the matchup, alongside the scoreboard clock and the clock on the wall. The effect is real, but narrower than sports talk usually makes it sound. Here is what the research actually shows, where it stops, and what it means for the 2026 schedule, including the Sunday America changes its clocks in the middle of Week 8.

The body clock behind the box score

Every player carries a circadian clock, a roughly 24-hour internal cycle that drives core body temperature, alertness, reaction time, and muscle output. Sleep researchers have long reported that several components of athletic performance peak in the late afternoon and early evening of a person's internal day and dip in the early morning. Two details matter for football.

First, the clock does not reset instantly when a team lands somewhere new. A common rule of thumb in sports chronobiology, also used as a modeling assumption in the studies below, is about one day of adjustment for each time zone crossed. NFL teams almost never stay away long enough to adjust fully. A West Coast team flying to the East for a Sunday game typically arrives Friday or Saturday, so its players take the field with their bodies still largely on Pacific time.

Second, the human clock runs slightly longer than 24 hours. That makes it easier to stretch the day (fly west, stay up later) than to compress it (fly east, wake up earlier). Northwestern University researchers led by Ravi Allada used this asymmetry to explain why, in their baseball data, eastward trips hurt and westward trips barely registered.

The Monday Night pattern Stanford found

The NFL's best-known body-clock finding comes from Monday Night Football. Roger Smith, Christian Guilleminault, and Bradley Efron of Stanford published it in the journal Sleep in 1997. They looked at every MNF game from 1970 to 1994 that matched a West Coast team against an East Coast team, all of them kicking off at 9:00 p.m. Eastern.

The logic behind that design is cleaner than it first looks. A nationally televised game has a fixed Eastern start time no matter where it is played. A 9:00 p.m. ET kickoff is 9:00 p.m. on an East Coast player's body clock and 6:00 p.m. on a West Coast player's body clock, whether the game is in Seattle or in New Jersey. The West Coast team plays near its physiological peak, while the East Coast team plays deep into its evening.

The results were strong. West Coast teams won more often and by more points per game, and they beat the Las Vegas point spread significantly more often than the odds predicted. The point spread is the key control. It already prices in team quality, injuries, and home-field advantage, so a team that consistently beats it is beating more than a raw win-loss record. The authors also found that the effect amplified the West Coast teams' home-field advantage and effectively erased it for East Coast hosts in these night games.

In 2013, Smith returned to the question with Efron, Cheri Mah, and Atul Malhotra in a larger study, also published in Sleep. They looked at 40 seasons, 1970 through 2011, and counted every game between East Coast and West Coast teams that kicked off after 8:00 p.m. Eastern. That gave 106 night games. West Coast teams beat the spread in 66 percent of them, by an average of 5.26 points against the line.

The finding everyone forgets: the 1 p.m. game

The same 2013 study also looked at daytime games between East and West Coast teams. It found no significant advantage for either side. This matters, because the most repeated piece of NFL body-clock folklore is that West Coast teams fall apart in 1:00 p.m. Eastern kickoffs, which feel like 10:00 a.m. to them. That may well be true for individual players, and some teams treat it seriously in how they schedule travel. But in this 42-season dataset, it did not show up as a measurable edge against the spread. The documented effect belongs to night games.

What the numbers do not prove

Both studies are observational. They show a strong and persistent pattern, but they did not control when teams traveled, how they slept, or what else happened in those games. A sample of 106 night games is meaningful but not huge. Most of the data also comes from an era before modern sleep staffs, chartered recovery protocols, and wearable sleep tracking. It is reasonable to ask whether teams have narrowed the gap since then, and whether betting markets have priced it in now that the finding is well known. No published study I can point to settles either question. Treat the 66 percent figure as a historical result, not a current betting rule.

Baseball and basketball point the same direction

Football plays one game a week, which limits the sample. Leagues that play almost every night offer much more data, and the results line up with the NFL work.

The baseball study is the most detailed of the group. Allada's team found 4,919 games in which a team had crossed at least two time zones without enough days to adjust. The damage was concentrated after eastward travel. The clearest single symptom was home runs allowed: jet-lagged home pitchers gave up roughly 0.1 extra home runs per game. The most surprising result was that the effect hit home teams returning from a West Coast trip, not just visiting teams. A team can be jet-lagged in its own ballpark. In a published reply, French researcher Etienne Joly pointed out that the paper documents correlations, not proven causes, and that criticism applies to this entire field.

The NBA study points the same way: performance improved after westward trips and declined after eastward ones. Its authors are upfront that they could not see actual team travel and had to model it, and that they did not adjust for team quality. An earlier conference abstract presented at SLEEP 2016 by Geneviève Forest and colleagues looked at five seasons of the NBA, NFL, and NHL. It found that visiting teams traveling west had lower winning percentages, especially in evening games. That fits the Monday Night logic: an East Coast team playing a late game out West is playing even later on its own body clock. Because it is an abstract rather than a full peer-reviewed paper, it is supporting evidence, not proof.

Across leagues and decades, the common thread is consistent. Body-clock effects are small per game, real in aggregate, and strongest when a late start meets an Eastern body clock or when a team has just come home from the West.

The 2026 international slate as a body-clock schedule

The NFL's record nine-game international schedule turns this from a lab question into a real one. The league sets most overseas kickoffs to fit American TV windows, so the local time can be far from what the players' bodies feel. The table assumes each team's body is still on its home time zone, which is roughly true for a team that arrives late in the week.

Three patterns stand out. The European games are effectively morning games for every American team. That is the time slot where performance research is least favorable, which is a big part of why many clubs now fly out early in the week to give their players time to adjust. The Melbourne opener was the reverse: a late-morning local kickoff that both California teams played in their late afternoon, close to the circadian sweet spot (the 49ers won 27 to 7). And the Mexico City game, played on Sunday night at more than 7,000 feet, recreates the old Monday Night setup: San Francisco plays at 5:20 p.m. on its body clock, Minnesota at 7:20 p.m. Altitude is a separate and probably larger factor, so this game will not cleanly test anything.

Notice also what happens to local kickoff times in Madrid and Munich. The NFL kept the 9:30 a.m. Eastern slot, but the US falls back on November 1, a week after Europe. A 9:30 a.m. Eastern kickoff was 2:30 p.m. in London and Paris in October. It becomes 3:30 p.m. in Madrid and Munich in November. The TV slot stays fixed, while the gap between continents changes underneath it.

Paris on the morning Europe changes its clocks

The Steelers-Saints game falls on the exact Sunday the European Union ends summer time. At 3:00 a.m. that morning, clocks in France go back to 2:00 a.m. For one week, until the US changes on November 1, Paris is five hours ahead of Pittsburgh instead of six. A team that spent the week adjusting to Paris time gets an extra hour of sleep the night before the game, and its local clock moves one hour back. In body-clock terms, that is a one-hour westward shift, the easier direction for the human clock. This is my inference from the general physiology, not a tested result for NFL games. Players on that trip should still double-check every wake-up call and meeting time on game morning, because phones update automatically and hotel room clocks often do not.

November 1: the Sunday America falls back mid-season

Daylight saving time ends in the United States at 2:00 a.m. local time on Sunday, November 1, 2026. That is the Sunday of Week 8. Every team gets an extra hour on Saturday night, which is about the friendliest form of time change there is. Kickoff slots do not move in Eastern time: the early games are still at 1:00 p.m. ET, the late games at 4:05 and 4:25 p.m. ET, and Sunday Night Football at 8:20 p.m. ET. For most fans the relationship to their local clock does not change either, because all four main US time zones fall back together.

Arizona is the exception. The state stays on Mountain Standard Time all year. Until November 1, the Cardinals effectively share a clock with Los Angeles: a 1:00 p.m. Eastern game starts at 10:00 a.m. in Phoenix, and a trip to the East Coast is a three-hour jump. From November 1, the same 1:00 p.m. ET kickoff is 11:00 a.m. in Phoenix, and the East Coast is only two hours away. In practice, the Cardinals spend the first half of the season as a Pacific-time team and the second half as a Mountain-time team. For a club that travels east several times a year, that change is worth noting.

For fantasy managers, the risk is administrative, not physical. Most platforms lock each player at his game's scheduled kickoff, and that time is stored in absolute terms. A manager in Phoenix who usually sets the lineup at 10:45 a.m. local "before the early games" has a cushion of 15 minutes until November 1, and an hour and 15 minutes after it. In October, the danger runs the other way. Overseas fans and managers who follow the NFL from Europe see the 1:00 p.m. ET window at 6:00 p.m. in the UK all season. On October 25 alone, the week the continents are out of sync, it arrives at 5:00 p.m. An easy way to avoid losing a starter to a time change is to check the kickoff in your own zone on WorldTimeData before setting the lineup. WorldTimeData shows current local times and the scheduled clock changes, so you can confirm the conversion instead of assuming it.

Using the body clock without overrating it

Fans, fantasy players, and analysts can take a few concrete lessons from the research, along with an equal number of warnings.

• The strongest documented NFL effect is narrow: Pacific teams against Eastern teams in games that start after 8:00 p.m. ET. In nationally televised night games, the venue matters less than the start time, because a fixed Eastern kickoff sets both teams' body clocks.

• Early Sunday games for West Coast teams are the most talked-about body-clock disadvantage, but the largest NFL dataset found no significant effect in day games. Treat them as a minor factor, not a reason to bench a starter.

• In baseball, the clearest risk is a home team just back from a trip out West, especially its pitchers. During the MLB postseason, when teams fly coast to coast between games, the travel schedule deserves a look before every series switch.

• European NFL games are morning games for the players' bodies. Whether a team arrives early in the week or late is often a better clue to how it will handle the trip than the matchup itself.

• A body-clock edge is a modifier, not a forecast. Even the striking 66 percent figure came from 106 games over 42 seasons. A single game can and often does go against it.

The interesting part is not that time zones decide games. It is that something as dull as a TV schedule can quietly give one sideline its 6:00 p.m. body and the other its 9:00 p.m. body, and that this difference has been measurable for half a century. In a league where the point spread already accounts for nearly everything else, the clock remains one of the few factors many fans still don't think about.