It’s sort of the inverse of another bowel-related vacation experience: traveler’s constipation. Many people find themselves clogged while they’re away from home, often because they’re uncomfortable pooping in unfamiliar bathrooms. It can also be because they are eating less poop-friendly foods on vacation, or because unfamiliar bacteria in a new environment are throwing off their gut microbiomes, as Mollie Bloudoff-Indelicato reported for The Atlantic in 2015. (Of course, if you eat the wrong meal, you could suffer traveler’s diarrhea instead.)
“In my view the experience of ‘unburdening’ upon returning from a trip is largely a Pavlovian response: The home is a safety signal, signifying that this is the right place to go,” Haslam told me over email. This is likely to be the case whether or not you were particularly constipated during your trip. “If there has been any inhibition or retention at all during the trip the relaxation response is likely to kick in when you come home,” he says.