Have you ever felt a little queasy when you were watching an action-packed 3D movie? There may be a medical reason behind it.

Vision researchers in Oregon enlisted adults of various ages to watch the same movie in 2D and in 3D, sitting at different angels and distances. Twenty-one percent of participants reported vision and motion symptoms while watching the 3D version, compared to just 12% who reported these symptoms while watching the movie in 2D.

Symptoms related to 3D viewing include double or blurred vision, dizziness, disorientation and nausea and were affected by where the participants sat and their age. Younger viewers who really got into the film suffered for it. Sitting right in front and looking straight ahead caused the most motion sickness. Older viewers actually had more motion sickness symptoms in 2D viewing.

The good news? Symptoms can be reduced if you sit farther back from the screen and at an angle.