We’re still not sure of the process by which motion sickness happens. Drugs for this condition have not changed for 60 years. The believed mechanism is a conflict of information between the inner balance sensors, visual, and proprioceptive systems. Those who suffer from motion sickness tend to rely predominantly on their visual system for balance. If you can’t see where you are going, for example while seated in the back seat of a moving car, your motion sickness gets triggered. If you drive, you see where you’re going and feel fine.
For similar reasons, watching things move can also be a major trigger. The brain wants stable vision. Watching moving objects causes problems for some. Examples include crowded situations, action movies, and scrolling computer screens. In these circumstances, the brain has no stable frame of reference. It becomes confused, resulting in nausea and/or dizziness.
We can help the brain by fixing our eyes on a stable object. In a crowd, try to focus on something that isn’t moving. If in a moving car, try to concentrate on a distant stationary object. Nearby objects that are rapidly moving will confuse the brain. Flashes of light or a pattern of light and shadow also trigger motion sickness.