Jet lag can be a problem for athletes who travel across time zones. Excessive fatigue and disturbances of the athlete's body clock can have effects on feelings of fatigue and performance. What exactly is jet lag? and what can we do about it? Below is an interview with Dr Shona Halson and Prof Neil Walsh based on a multi-author review paper on sleep and jet lag that was recently published in the British Journal of Sports Medicine (1).
What is jet lag exactly and what causes it?
Jet lag follows travel across multiple time-zones and is caused by desynchronisation of the circadian system to the new external environment at the destination. The human circadian system requires time to adjust, leading symptoms such as sleep disruption, daytime fatigue, gastrointestinal disturbances and reduced performance.
What are the symptoms of jet lag?
Travel fatigue is associated with high frequency travel and jet lag is associated with time zone displacement. The symptoms of travel fatigue and jet lag may be similar, but different aspects of travel cause them. Travel fatigue is associated with the disruption and demands of travel, such as getting to the plane and is often an issue for elite competitors in sports such as basketball (National Basketball Association) and hockey (National Hockey League), who travel extensively. Jet lag is associated with the resynchronisation of the body clock to the new environment and resolves at a rate of about 1 day per time zone crossed.
What is the effect of jet lag on performance in various sports?
We don’t have much evidence in elite athletes that jet lag affects performance. We know they have symptoms, but whether this translates to poor performance is not as clear. The best evidence for a relationship between jet lag and performance is from teams who travel extensively and we know that teams travelling westward for evening matches have a disadvantage.
Does traveling East or traveling West make a difference and why?
It is generally considered that westward travel is easier to adjust to. After westward travel, the circadian system will be ahead of the local time zone. To adjust to the, the circadian system has to delay, or shift backward. After eastward travel, the circadian system will be running behind the local time zone, so to adjust to the new time zone, the circadian system has to advance, or shift forward which may be more difficult.
It is generally considered that westward travel is easier to adjust to. After westward travel, the circadian system will be ahead of the local time zone.
Can we do anything nutritionally to minimise the effects? What about medication?
From our recent systematic review in BJSM on managing travel and jet lag, we found that current recommendations for managing jet lag appear to be based on opinions, collective experience and results from laboratory-based studies on non-athletes. So, no good evidence for nutrition or medication.
What would be your travel advice for athletes who travel long haul?
The best evidence suggests that appropriately timed light exposure/avoidance and ingestion of exogenous melatonin help facilitate adaptation best.
Getting good sleep prior to travel, remaining hydrated during travel and getting into the new destinations time zone can all be helpful.
Walsh NP, Halson SL, Sargent C, et al. Sleep and the athlete: narrative review and 2021 expert consensus recommendations. British Journal of Sports Medicine Published Online First: 03 November 2020. doi: 10.1136/bjsports-2020-102025