It’s tough to follow the dosing instructions for sleep aids while on a plane and unfortunately that sometimes results in negative consequences for travelers, report CNN.

Travelers often make the possible side effects worse by combining them with tranquilizers and alcohol, said Dr. Rajkumar Dasgupta, an assistant professor at the Keck School of Medicine at the University of Southern California.
“The worst thing you can do is drink alcohol on a plane,” Dasgupta said. “You’re already dehydrated, you have a lot of travel fatigue, and on top of that you’re adding sleeping aids to it.”