Top-level chess players are constantly travelling from one continent to another to attend over-the-board tournaments. The effect of jet lag has not been investigated. While individuals have a highly variable ability to recover from jet lag, we can study the average effect. I have analysed 26k games between players above 2650 Elo, using the time zone of the tournament, and the home time zone of each player. Potentially, both can be subject of jet lag.

The findings are interesting: If a player has travelled East more than his opponent (by at least four time zones), he scores about 1% less than his opponent during the first round. This normalises for the rest of the tournament. In chess, white has an advantage and scores about 56%. 1% is quite large with respect to that, we can think of the white advantage being increased by 16% if black is more jet-lagged.

• If white has travelled East more than black (by at least four time zones), the average score is 0.57
• If no player has a lag ‘advantage’ over the other, white scores 0.56
• If black has travelled East more than white (by at least four time zones), the average score is 0.55
• The results normalise back to an average for the rest of the tournament.

Why is travelling East more difficult

Travelling West requires lengthening one’s circadian cycle to adapt, and travelling East requires shortening one’s cycle. Given that the average circadian cycle is slightly longer than 24 hours (24.18) for most people travelling West is a lot easier to adapt to. Note that there is some evidence that in American sports the team travelling West is advantaged. The mechanism at play is different as the lag difference is smaller than the one we look at here and the performance difference can be explained by time-of-the-day effects at which the body performs better for exercise.

Interventions to mitigate jet lag

There are several avenues to fight jet lag, mostly:

• Light exposure. Being exposed to light outside, i.e. a natural source of light, has a powerful effect on the brain, and appropriate exposure can help re-set the circadian clock.
• Exercise and nutrition timing can help re-set the circadian clock.
• Pharmacological interventions should only be conducted under medical supervision and I would not recommend them without careful consideration. While some can be easier to understand (for example, the use of caffeine), use of melatonin is possible, but more complex. Be wary of the legal status of any medication you carry while travelling to foreign country.

If you would like help to implement anti-jet lag strategies and/or sleep hygiene, do not hesitate to get in touch.