Flying across multiple time zones — particularly from west to east — can wreak havoc with your body’s biological clock, resulting in insomnia, fatigue and a decline in cognitive function or physical performance.
Jet lag, as the phenomenon is known, upsets the body’s circadian rhythm, the 24-hour cycle that regulates sleeping, waking and eating.
“When someone travels across at least two time zones at a time, they end up with a mismatch between their internal circadian clock and the day/night, sleep/wake cycle of their new destination,” said Khalid Ismail, MD, Director of the Sleep Center and Sleep Fellowship Program at Tufts Medical Center, and Assistant Professor of Medicine at Tufts University School of Medicine.
“It is usually worse when you are traveling in an eastbound direction,” he noted.
Luckily, jet lag does not occur traveling north to south or south to north.
Impact on Performance
A study published earlier this year in the Proceedings of the National Academy of Sciences by researchers at Northwestern University showed that baseball players who traveled two or more time zones before a game saw their performance affected in a variety of ways.
Players from east coast teams who had just returned from a west coast trip had fewer stolen bases, doubles and triples and hit into more double plays than those who hadn’t recently traveled. Pitchers also gave up more home runs after traveling eastward.
Here’s an example: Let’s say you fly from Boston to Paris, where it is six hours later. If you land at 10 p.m. Paris time, internally, it is still 4 p.m. for your body. Going to sleep at that time would be quite difficult.
“People around you might be asleep, but your internal clock wants you to stay awake,” Dr. Ismail said. “Or it may be the opposite - people around you are awake but your internal clock is set to sleep.”
The body cannot adjust that rapidly, so one might become jet-lagged. Traveling westward is physiologically gentler because, for most individuals, it is easier to delay going to sleep than to fall asleep earlier than usual, he noted.
Most body functions become out of step with your destination time zone. In addition to insomnia, fatigue, and a decline in performance, symptoms may include headaches, irritability, loss of appetite and constipation.
There are a few things you can try to prevent jet lag, or deal with it when you arrive at your new time zone, Dr. Ismail said. Frequent travelers, like pilots and flight attendants are advised to stick to their home schedules. Less frequent travelers may try going to sleep 30 minutes to an hour earlier than usual each night for a few days before their eastbound travel.
Some people may benefit from taking melatonin an hour earlier every night prior to their trip and continue to take it once they arrive, he said. It can help advance sleep onset in preparation for eastward travel.
Dr. Ismail also stressed the importance of bright light exposure and its effect on stimulating wakefulness. When arriving mid-day to an eastern destination, for example, use sunglasses to avoid light effect on delaying sleep at night.
If you are going to attend an important meeting soon after landing, coffee may help. It is also important to keep hydrated and avoid alcohol.
Travelers may want to take a sleeping pill on the plane, but he advises against doing so unless the traveler has taken the pill before, knows how his or her body reacts to it, and can gauge how long it might affect performance.
Finally, Dr. Ismail noted the availability of new smartphone applications to help fliers plan for a trip by creating a gradual sleep/wake schedule that best fits their destination time zone, and reduce the effects of jet lag.
“We are going to see more of this, both wearable technology and smart phone apps, which will help people deal with this relatively common problem,” he said.
Posted November 2017
The above content is provided for educational purposes by Tufts Medical Center. It is free for educational use. For information about your own health, contact your physician.