New Study Finds Link Between Jet Lag, Performance

What happened to Clayton Kershaw in Game 6 of the NLCS? According to a new study by Northwestern University, maybe it was jet lag.

Looking at 20 major-league seasons and 40,000 games’ worth of data, researchers found that jet lag perceptibly “impairs” player and team performance. The study is likely to be passed around many major-league front offices and strength-and-training departments. In a sport where every team is looking for hidden value at the margins, the value of better rest and recovery is just beginning to be explored, understood and focused upon — and is perhaps a considerable inefficiency in the game.

Dr. Ravi Allada, a circadian-rhythms expert, led the study:

“The negative effects of jet lag we found are subtle, but they are detectable and significant. And they happen on both offense and defense and for both home and away teams, often in surprising ways….

“For Game 6, the teams had returned to Chicago from LA, and this time the Cubs scored five runs off of Kershaw, including two home runs. While it’s speculation, our research would suggest that jet lag was a contributing factor in Kershaw’s performance.”

One of the homers in question:

Of course, Kershaw did pitch on extra rest that start, and Kyle Hendricks himself did just fine after traveling back east, but perhaps the rest could not save Kershaw from the clutches of jet lag.

The study found that jet lag is a more powerful detrimental force when traveling from west to east. “This is a strong argument that the effect is due to the circadian clock, not the travel,” Allada said.

Allada and his researchers found the most impairing effects of jet lag, in terms of run production, were tied to baserunning inefficiency.

They found the influence of jet lag on pitchers most often manifests itself in the form of home runs allowed. “The effects are sufficiently large to erase the home-field advantage,” Allada said.

Perhaps most interesting from the study is the suggestion that pitchers should more often fly on commercial flights a day or two ahead of the team, and not on the team charter.

“If I were a baseball manager and my team was traveling across time zones — either to home or away — I would send my first starting pitcher a day or two ahead, so he could adjust his clock to the local environment,” Allada said.

Pitchers occasionally fly a day ahead of a team, but it’s not a regular practice, and I’m not aware of pitchers flying out two days ahead of time. Perhaps Kershaw should have flown out earlier, say on October 20, and enjoyed two days on the Magnificent Mile before his Game 6 start?

Of course, teams are already interested in combating travel fatigue, and fielding better rested, better recovered players.

In addition to a celebration room in their new Wrigley Field clubhouse, Cubs players also enjoy a “quiet room” with three beds, a place to rest and recover. In the NBA, the Golden State Warriors are among the teams on the vanguard of studying rest and recovery and putting practices in place. And, interestingly, home-court advantage is on the decline in the NBA. “Teams are smarter about their travel habits and getting rest these days,” Dallas Mavericks owner Mark Cuban told ESPN. “Guys aren’t going out as often, so the road just isn’t as hard as it used to be.” Still, some believe certain NBA game outcomes are almost pre-determined due to travel and schedule considerations.

I know the Pirates are invested in rest and combating jet lag from my time covering the organization.

While on a road trip in Seattle covering the Pirates last season, my conversation with Jared Hughes in the Safeco Field clubhouse turned to his preferable type of sleeping eye mask. There was a relevant purpose to the interview.

I was reporting on a story about how teams deal with travel. Given that the Pirates were three time zones and 2,100 miles away from PNC Park, and in the midst of grinding stretch of 46 consecutive days of games or travel without a true off day, it seemed like an appropriate time.

I had been given a mask by my wife for an overnight flight to Europe a few years earlier, and while initially opposed to the idea, I felt it helped me sleep better by reducing light. I’ve adopted the mask as a regular practice.

“The key is the foam kind which does not touch your eyes. It’s really nice.” Hughes said of the eye mask. “It helped me sleep until 10 a.m. (Tuesday) because it was dark.

“Not everyone does it. I know some guys don’t like how it feels on their face.”

Not every player wore a mask, but all of them had been made aware of its benefits. Pirates players had met with sleep “experts” during spring training, who had advised players on the benefits of masks, traveling with their own pillow, and how to adjust to traveling across time zones which can disrupt our natural circadian rhythms.

On the first night after arriving to the Pacific time zone, Pirates shortstop Jordy Mercer said he plays Xbox to force himself to stay up later – while avoiding caffeine – to combat the disruption to his circadian rhythm.

“(The sleep experts) told us when we go east to west, the first night stay up as late as you can and force yourself to get used to it,” Mercer said of the sleep consultants. “That’s the biggest thing I took out of it… Get somewhat acclimated to the time change.

Before arriving in Pittsburgh, head athletic trainer Todd Tomczyk worked for innovative sports medicine and training staffs with the Los Angeles Dodgers and Cleveland Indians. He’s curious about many things that can help players rest and recover. He even educated players about how blue wavelengths from smart phones and electronic devices can be disruptive to sleep. The Harvard Medical School has researched the dark side of blue light. The lesson? Always keep your smart phone on night mode.

“It masks the blue light,” Tomczyk said.

Others outside pro sports industries are also studying how to best rest and recover.

One of my first pieces at FanGraphs was tied in part to rest and recovery issues in examining whether home field advantage is becoming endangered. I spoke with Whoop CEO Will Ahmed, whose wearable technology start-up company studied more than 200 minor-league players last year. While the study wasn’t focused on jet lag, the study did find insufficient rest and recovery can have a quantifiable influence.

Ahmed found that, when athletes return home from a road trip, or traveled a distance for a road trip, they required two days to adjust. That’s similar to finding of the Northwestern study.

“We found that athletes, when traveling, on average got an hour less sleep than athletes that did not travel,” Ahmed said. “An hour less in bed, 45 minutes less sleep. That’s about 10% lower recovery. Conventional wisdom says the home team wins because they have their fans supporting them or they are playing in a familiar park. The study suggests the home team may win because they are better recovered and well-rested…

“There was a direct correlation between the higher your recovery and the faster your exit [batted ball] velocity. We found the same correlation with pitchers and fastballs,” Ahmed said. “I didn’t know for sure we were going to see such strong correlations with travel, recovery and performance. Those were a bit of a eureka [moment] with us and for people in Major League Baseball who saw this study.”

The next big thing in the majors might deal with how to extract more efficient performance from players. It might in part be tied to better understanding of rest and recovery, it might be tied to information from the wearable technology wave.

And if the Cubs and Dodgers meet again in the postseason, perhaps Kershaw will be flying out a day or two earlier for his start.





A Cleveland native, FanGraphs writer Travis Sawchik is the author of the New York Times bestselling book, Big Data Baseball. He also contributes to The Athletic Cleveland, and has written for the Pittsburgh Tribune-Review, among other outlets. Follow him on Twitter @Travis_Sawchik.

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Very interesting Travis.

Would it be possible to do a follow-up post quantifying the findings? I am working my way through the paper but the walls of text make it difficult to decipher in a concise manner.

My own thoughts on jet lag, I am interested if there are quantifiable impacts on relief pitchers specifically traveling west for late games. Games that start at 10 pm EST and end at 1 am EST. Every year a small handful of college football teams from the Eastern and Central time zones travel to the west coast to play a late game and my anecdotal bias has led me to believe they suffer in the 2nd halves of these games. Similarly west coast teams traveling to the east coast for a noon kickoff getting off to incredibly slow starts in a game that feels like it starts at 9 am.