Why does reading in a car make you feel sick?

Reading amplifies the sensory conflict at the heart of motion sickness. The vestibular system in the inner ear detects every bump and turn, but the eyes are locked onto a stationary book or screen. The brain expects those signals to match, and when they don’t, it may trigger nausea. Looking out of the window solves the problem because the eyes then confirm the motion the inner ear feels. Peripheral vision also plays a role: when your visual field is dominated by a still page, the brain loses the motion cues it needs. Audiobooks and podcasts avoid the problem entirely because they don’t require the eyes.