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Jet Lag

What is jet lag?

Jet lag is the tiredness you may feel after flying long distances across several time zones. The rapid travel to a different time zone disturbs your normal body rhythms.

How does it occur?

Your body has an internal clock that determines when you eat, sleep, and wake up each 24-hour day. When you travel across several time zones, your "day" is longer or shorter than 24 hours. Your body is out of sync with the local time zone. It takes some time for your body rhythms to adjust to this shorter or longer day. While you are adjusting, you may feel jet lag.

Not all jet lags are the same. Flying eastward, which shortens your day, is harder to adjust to than flying westward, which lengthens the day.

What are the symptoms?

The symptoms of jet lag may include:

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  tiredness
  
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  drowsiness during the day
  
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  trouble sleeping at night
  
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  not feeling sharp mentally and having trouble concentrating or remembering things
  
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  feeling irritable
  
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  headaches
  
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  indigestion or a change in appetite or bowel habits
  
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  minor coordination problems and reduced physical stamina
  

How long will the effects of jet lag last?

You may feel the effects of jet lag for up to a few days after your flight, depending on how many time zones you crossed. In general, the more time zones you cross, the longer it takes to recover.

You may find it easier to adjust to new time zones if you break up a long journey with a stopover partway to your final destination.

If you have an important event or meeting to attend at your destination, try to get there 2 or 3 days early.

What can I do to help prevent jet lag?

Here are things you can do to help reduce the symptoms of jet lag:

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  Try to get plenty of rest before your trip.
  
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  Schedule your arrival at about your usual bedtime, according to the time at your destination, or sleep on the plane and plan to arrive at your usual waking time.
  
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  If you are going to fly east, try going to bed earlier than usual for a few days before the trip. If you are flying west, go to bed later than usual.
  
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  Drink plenty of water and other nonalcoholic drinks before, during, and after your flight.
  
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  Set your watch to the destination time when you are halfway through your flight, so you can start thinking in terms of the new time.
  
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  If you are flying at night, use an eye mask and ear plugs to help block light and sound so it may be easier to sleep.
  
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  Spend more time outside at your destination. This exposure to bright outdoor light will help you to adjust faster than if you stay in your hotel room.
  
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  No matter how tired you are when you arrive, try not to sleep until it is nighttime at your destination.
  

How do I adjust medicines prescribed for a certain hour?

If you are diabetic and use long-acting insulin, you may have to change to regular insulin until you have adjusted to the time, food, and activity of your destination.

You may have to adjust other medicine schedules according to the actual hours between doses rather than the local time at your destination. Ask your healthcare provider about this.

Patient handouts provided by Merck Medicus. Copyright © 2012-2013 Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc.