Jet lag and training: how to stay fit across time zones
The short answer
Jet lag is the mismatch between your body clock and local time after crossing time zones.
Read the full answer
It causes poor sleep at night, sleepiness by day, reduced concentration and digestive upset, and it is usually worse after flying east. As a rule of thumb, the clock shifts by about one time zone per day, a little faster westward. You can speed the adjustment by switching to local time on arrival: get daylight, eat at local mealtimes, stay awake until a reasonable local bedtime and keep naps short. For training, do easy sessions for the first days, outdoors and in daylight if possible, and postpone hard sessions until you are sleeping normally. For a trip of two or three days, the British National Health Service suggests it may be simpler to stay on home time. Dubai sits three or four hours ahead of western Europe and eight to nine ahead of New York.
How many days to get over jet lag?
Two answers, and you know how long your body needs to adjust and when to go back to hard sessions.
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One time zone usually means one hour of time difference.
Which way are you flying?
Your result
About 8 days
Days to adjust, rule of thumb
Allow about 8 days to adjust. Wait about 4 days before a hard session.
- Hard sessions
- Wait about 4 days
A rule of thumb, not an official standard. Individuals adjust at different rates.
What is happening
Almost every function of the body follows a daily rhythm set by an internal clock: sleep and wakefulness, body temperature, hormone release, digestion, alertness, muscle strength. The clock is synchronised each day mainly by light.
After a flight across several zones, the clock is still on home time. You are asked to sleep when it signals wakefulness and to perform when it signals night. The clock then shifts gradually towards local time, guided by light exposure.
Flying east requires advancing the clock, falling asleep earlier, which the body finds harder than delaying it. A flight from Dubai to London or New York is usually easier than the return.
Travel fatigue is a separate matter. A long flight north to south across no time zones leaves you tired, dehydrated and stiff, and one good night resolves it.
How long it takes
The figure of one day per time zone is a widely used approximation, not an official standard, and individuals vary. The planner above applies it, with a somewhat faster rate for westward travel.
- Up to two zones: little or no jet lag.
- Three to five zones: two to five days of partial disruption. Dubai to western Europe falls here.
- Six to nine zones: up to a week or more. Dubai to the east coast of North America, or to east Asia.
Light is the main tool
Light at the right time moves the clock in the right direction; at the wrong time it moves it the wrong way.
- After flying east, seek light in the local morning and avoid bright light late in the evening.
- After flying west, seek light in the late afternoon and evening, and stay up until local bedtime.
After very long eastward journeys, early-morning light on the first day or two can fall at a point that pushes the clock the wrong way. Sunglasses for the first morning hours, then daylight from mid-morning, is the usual advice.
Sleep
- On the aircraft, set your watch to destination time and sleep when it is night there, if you can.
- On arrival, stay awake until at least 10 pm local time.
- Keep naps under thirty minutes and before mid-afternoon.
- Rise at a fixed time, even after a poor night. The second night is nearly always better.
Melatonin is used for jet lag and has reasonable evidence for eastward travel. Its status differs between countries, and it interacts with some medicines: ask a physician or pharmacist. The National Health Service does not routinely recommend it. See sleep for executives.
Training in the first days
Exercise does not reset the clock as strongly as light, but it helps in three ways: it gets you outdoors in daylight, it relieves the stiffness of the flight, and it improves the following night.
- Day of arrival: a 20 to 30-minute walk outdoors. Mobility work for hips and back.
- Days two and three: easy aerobic work, or a light strength session at reduced loads.
- From the day you sleep through the night: normal training.
Strength and reaction time follow the body clock. A hard session at what your body takes for three in the morning is poor training and carries a higher risk of injury. If a session must be hard, place it at a time that corresponds to your home afternoon.
Food and drink
- Drink water through the flight. Cabin air is dry. See hydration.
- Go easy on alcohol on board. It worsens sleep and dehydration. See alcohol and training.
- Use caffeine deliberately: in the local morning, to stay awake, and not after early afternoon. See caffeine.
- Eat at local mealtimes from arrival. Meal timing is a secondary signal for the body clock.
Short trips
For a stay of two or three days, adjusting and then readjusting costs more than it gains. The alternative is to remain on home time as far as the schedule allows: sleep and eat at your usual hours, arrange important meetings when you would be alert at home, and train lightly.
People who travel constantly
Someone who crosses five zones twice a month is rarely fully adjusted anywhere. The priority shifts from adaptation to protection.
- Guard sleep duration above all. See the debt calculator in sleep for executives.
- Keep training simple and portable. See the hotel room workout.
- Accept maintenance on travel weeks and progress on home weeks.
- Schedule the hard decisions and the hard sessions for the days when you are on your own clock.
When to see a physician
Persistent insomnia, low mood or digestive problems that do not settle within two weeks of returning deserve attention. So does the regular use of sleeping tablets on flights, which carries its own risks.
A coach who knows your travel schedule adjusts the week before you leave, not after you return. How the Club works.
Questions
How long does jet lag last?
As a rule of thumb, about one day for each time zone crossed, somewhat less after flying west. A trip from Dubai to London, three or four zones, takes a few days. Dubai to New York, eight or nine zones, can take a week or more. Individuals vary, and the figure is an approximation rather than an official standard.
Should I exercise when I am jet-lagged?
Yes, gently. A walk outdoors on the day you arrive exposes you to daylight, eases stiffness and helps the next night's sleep. Keep sessions easy for the first two or three days, and return to hard training once you are sleeping through the night. Strength and coordination are reduced while your body clock is out of step.
Is jet lag worse flying east or west?
It is usually worse flying east. Travelling east requires falling asleep and waking earlier than your body clock expects, and advancing the clock is harder than delaying it. After a westward flight you need to stay up later and sleep later, which most people manage more easily. The return to Dubai from the Americas is the difficult direction.