What causes nausea?

Q: What induces vomiting when we travel or look down from a height?

A: Giddiness occurs when we lose our sense of balance. The sensations perceived by the eye, the inner ear, the skin, the muscles, and joints help the body to know whether it is stable.

Several unusual situations, such as travelling in a bus or looking down from a great height, overstimulate and confuse the part of the brain that controls balancing. This part is close to the part that induces vomiting.

When we look down from a great height, abnormal visual signs are transmitted to the brain, without any corresponding information from other parts of the body.

Likewise, while looking out in a fixed direction while travelling in a bus, the eye sends rapidly changing visual signals to the brain. Such signals confuse the mechanism in the brain, leading to giddiness and vomiting.

– B. Kavitha, Chennai