Jet lag

Jet lag is a combination of fatigue and other symptoms caused by traveling abruptly across different time zones. Another name for it is “time zone change syndrome”.

The body is synchronized to night and day by the action of sunlight through brain chemicals or neurotransmitters, especially melatonin. Many bodily processes are timed on this 24-hour physiological “clock”, including temperature, hormones, digestion, heart rate, blood pressure and brain states. This changing rate of activity over each 24-hour period is called the circadian rhythm (“circadian” means approximately one day).

Traveling to a different time zone disrupts the circadian rhythm. Lack of sleep before and during travel can also contribute to jet lag. There is no cure, but its effects can be reduced with careful planning.

Symptoms of jet lag#

Symptoms of jet lag can include:

• fatigue and sleepiness
• apathy
• digestive upsets
• impaired judgement and decision making
• memory lapses
• irritability

Flying east or west makes a difference#

Your circadian rhythm (body clock) is less confused if you travel westward. Traveling west “prolongs” the body clock’s experience of its normal day-night cycle, because the body clock in most of us tends to run slightly longer than 24 hours. Traveling eastward runs in direct opposition to the body clock. If you suffer badly from jet lag, it may be worthwhile considering a westerly travel route if possible.

There is no evidence that popular strategies, such as fasting or following complicated diets, have any effect.

Strategies to reduce the impact#

Suggestions to reduce the impact of jet lag while traveling include:

• Make sure you have had enough sleep before you leave, as a sleep deficit or “debt” will make jet lag worse.
• If you are flying westward, try to go to sleep as late as possible for two to three days before you leave, as this will make it easier to adapt to the new location.

During the flight#

• Limit or avoid alcohol and caffeinated drinks.
• Drink plenty of water.
• Try to nap whenever you feel sleepy.
• Eat small meals frequently, choosing lighter foods like fruit and vegetables.
• Wear loose, comfortable clothing.
• Whenever possible, walk around the cabin.
• When you sleep on the plane, try to plan sleep as if the time is that of your destination.
• Wear earplugs and an eye mask, and use a pillow to support your neck and head.

Adjusting to the new time zone#

The internal body clock of a jet-lagged traveler is out of synchronization with the new time zone and is still operating on “home time”. Different bodily processes adjust at different speeds, which adds to the confusion. Depending on the individual, the body needs anywhere from a few days to a few weeks to acclimatize.

Suggestions for adjusting include:

• Expose yourself to daylight, or to bright light if daylight is not available, to help “reset” your body clock. The stimulus that resets the clock is light entering the eyes, especially the blue spectrum of light.
• Drink caffeinated drinks in moderation during the day, but avoid alcohol or caffeinated drinks for a few hours before sleeping at night.
• Try to mimic your usual bedtime routine.
• Use relaxation techniques.

Alcohol, medications and jet lag#

Using medication is controversial and should be discussed with your doctor. There have been reports of some benefit from either melatonin or very short-acting sedatives, and melatonin has been shown to help some people adjust faster to changes in time zone.

It is not recommended that you use sleeping tablets during your flight, in case of an emergency. Some travelers use alcohol to help them get to sleep, but this actually disrupts the normal sleep cycles and can prolong jet lag.

Key points#

• Jet lag is a combination of fatigue and other symptoms caused by traveling abruptly across different time zones.
• Symptoms of jet lag include fatigue, sleepiness, apathy, digestive upsets, impaired judgement, memory lapses and irritability.
• The body needs anywhere from a few days to a few weeks to acclimatize to a new time zone, roughly one day for each hour of time zone change.
• Strategies include maximizing your exposure to daylight to “reset” your body clock and napping briefly during the day when sleepy.

Where to get help#