As a car passenger, boredom often tempts us to grab a book or phone. But soon, headaches or nausea hit. Neurologist Dean Burnett, author of Idiot Brain, unpacked this on NPR's Fresh Air on August 2, 2016.
During movement, muscles and the inner ear send signals to the brain via the thalamus, alerting us to motion in all directions. In a car or plane, however, muscles detect no effort since you're passively transported. Yet the inner ear registers the motion accurately. This sensory mismatch baffles the brain: how can you be still and moving? It interprets the conflict as neurotoxin poisoning—cue the vomit reflex to expel it.
Not everyone suffers motion sickness, and children are hit harder as their brains develop. Drivers often fare better, as their eyes confirm the motion. But reading? That's worse. Fixating on a stationary page or screen while your inner ear senses sway heightens the confusion: eyes say still, ears say moving. If cars already unsettle you, skip the reading—opt for other distractions instead.
