When you use a VR headset, your brain sees things in a strange way, and the focus is closer to your eye, which makes your eye work harder.
False positives happen when the brain thinks the body is moving when it is not. This can cause motion sickness or vertigo.
The vestibular system in the inner ear keeps the body balanced. When wearing a VR headset, these signals can get mixed up, throwing the body off balance and making it feel dizzy.
When you look at fast-changing or moving lights, your eye muscles can get hurt. This makes it hard to stay still.