What causes jet lag?

The circadian clock controls the timing of most behavioral and physiological rhythms

Most life on earth is adapted to the daily light/dark cycle caused by the rotation of our planet. We have an internal, 24-hour circadian clock located in the hypothalamus part of our brain that helps us anticipate and adapt to the regular rhythm of the day. Jet lag is caused when the sleep/wake and light/dark cycle shift too quickly for our circadian clock to keep up.

Jet lag comes with significant consequences.

Jet lag consequences for business travelers

Jet lag consequences for athletes and sports teams

Light is the most important time cue for resetting your circadian clock.

The right light exposure at the right time can significantly accelerate your adaptation to a new time zone. Seeing light at the wrong time will make your jet lag worse.

Light is the most important time cue for eliminating jet lag and adapting to a new time zone quickly

Melatonin can help you shift to new time zones even faster.

Taking melatonin at the right time can help you shift faster and sleep better when you are transitioning between time zones by telling the brain to sleep at a different time than normal.

Use of melatonin can help you to fall asleep more easily, stay asleep longer, and speed up adaptation to a new time zone

How timed light and melatonin affect your circadian rhythm.

Ways to increase your energy level while traveling

Caffeine

Caffeine is a powerful stimulant and can help you stay awake at times when you should see light, to help reset your clock more quickly. But be careful, using caffeine at the wrong time can have negative effects on your sleep quality.

Napping

Naps can be an additional tool to help maintain high levels of alertness and performance but they need to be scheduled at the right time to give you maximum recovery without affecting your scheduled night-time sleep.

What travelers do today (and why it isn’t working).

Follow generic advice

Jet lag receives a lot of media attention, but most tips shared in the media are generic, incorrect, and won’t help.

Use sleep medication

Sleep meds might help you fall asleep faster, but they don’t shift the clock, and you need to know the right time to sleep to reset your circadian rhythm.

Use stimulants

Caffeine can help with travel fatigue, but you need to know when to use it and when not to use it to minimize negative effects on sleep.

Trust airplane lighting

"Jet lag LED lighting" on new airplanes looks great, but often delivers the wrong light at the wrong time.

Travel business class

Being able to sleep well in business class is a great benefit, if you know when to sleep to maximize the circadian resetting.

Stay at 5-star hotels

While 5-star hotels provide good mattresses and pillows, they don’t address the underlying circadian disruption.

Schedule recovery days

People schedule recovery days to get over their jet lag, but these are not needed if you know how to shift your clock back to normal quickly.

You are unique,
and so is your jet lag.

Associate Professor of Medicine at Harvard Medical School and renowned expert in circadian rhythms, sleep and jet lag, Steven W. Lockley, Ph.D.

"The problems caused by jet lag cannot be tackled using generic advice, which is oversimplistic and can often be counterproductive, making jet lag worse. Each traveler and trip is different and requires a personalized approach taking your sleep pattern, chronotype, flight plan, and a range of personal preferences into account."

Steven W. Lockley, Ph.D.
Associate Professor of Medicine at Harvard Medical School

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