Motion sicknessedit this page
From Memory Alpha, the free Star Trek reference
Motion sickness is a physiological condition in which a disagreement exists between visually perceived movement and the vestibular system's sense of movement.
In 2375, The Doctor claimed he was suffering from "a little motion sickness" while traveling at transwarp in the Delta Flyer. He needed to adjust his matrix to accommodate for the extreme velocity. (VOY: "Dark Frontier")