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Discussing digestive function, or “gut movement,” at the dinner table may be uncomfortable, but moving—or not moving—your bowels can be equally painful. Regular bowel movements, constipation and diarrhea are influenced by many daily activities, including when you eat your meals. Throw travel across several time zones into the mix and you may be in for a ride on the intestinal roller coaster. That’s because gut movements are governed by circadian rhythm, the 24-hour internal clock that tells the body when to wake up, sleep, eat and do pretty much everything else.

The body’s circadian clock responds primarily to light, so changing time zones can negatively affect it. Travelers may experience jet lag, a feeling of daytime sleepiness or a general sense of not feeling well. Jet lag is not limited to fatigue and often also disrupts normal gut movement due to changes in eating as well as sleep patterns. If you’re traveling overnight, you may have the urge to snack at times you normally wouldn’t be eating or you may feel full without having eaten. Loss of appetite and constipation often go hand in hand because the gut sends signals to the brain and suppresses the urge to eat. On the other hand, eating a meal during normal sleep hours can sometimes lead to indigestion or heartburn.

Because traveling often changes what and when you eat, you may be introducing new foods and bacteria to your digestive system. The bacteria that live in your gut are called the microbiome. These stowaways help to maintain health inside and outside of the gut. Each microbiome is as unique as a fingerprint and changes with illness and medications, exercise and even location. When new foods and changes in your microbiome are paired with eating on a different time zone schedule, traveler’s diarrhea often strikes.

Stay healthy and keep your gut on schedule when you travel by:

• drinking plenty of water, which will also help ease constipation,
• eating a meal before boarding your flight. Try not to eat too much during the flight to prevent indigestion and urgent bathroom trips, and
• eating and sleeping according to your destination time zone as soon as possible. This resets circadian rhythms and helps your body adjust to the new time.

Being friendly to your gut may keep it much happier on your next high-flying adventure

Jessica C. Taylor, PhD, is a cardiovascular physiologist who manages projects for a contract biomedical research organization.