Gravol is a Antihistamine, antiemetic. Its used for sleep aid and motion sickness. both contain equal amounts of Dimenhydrinate
If your drowsy id recomend walking around. If it was only one then you shouldnt have a problem. When taken in high doses you wouldlt be able to move. It has a high tolerance for abuse. I would just drink some coke or more pepsi's and try to stay awake i guess