Motion sickness happens when the movement you see is different from what your inner ear senses. This can cause dizziness, nausea, and vomiting. You can get motion sick in a car, or on a train, airplane, boat, or amusement park ride.

Train-induced motion sickness is caused by a sensory conflict between what your eyes see and what your inner ear (vestibular system) feels. While your inner ear senses the swaying, vibration, and acceleration of the train, your eyes may be focused on a stationary object inside the car, such as a book or a phone. This "mismatch" causes the brain to trigger a nausea response, a primitive defense mechanism against perceived poisoning. On trains, this is often exacerbated by "backward-facing" seats, where the visual flow of scenery contradicts the forward momentum your body feels. Tilting trains (like the Pendolino) or double-decker cars can also create a more pronounced "sway" that confuses the brain further. To combat this, it is recommended to sit in a forward-facing seat, look out the window at the distant horizon rather than nearby objects, and stay in the middle of the train car where the motion is least intense.