Travel, sleep loss, and stress can all wreak havoc on our immune systems, reports Popular Science.

“I would imagine that being chronically sleep deprived and overworked and stressed would lower anyone’s resistance to infection,” said Christopher Sanford, an associate professor of family medicine and global health at the University of Washington.

In fact, travel in general may expose people to all kinds of conditions that could make them more susceptible to illness, whether or not they’re running for president of the United States.