Most importantly, you should understand why you get the headache in the first place. In traditional 2D movies, the out of focus areas of a scene often have coll little details and info in them that we’ve been conditioned to look at, the action occurring behind the hero, etc. When parts of the picture appear 3D to us, our simple monkey brain gets confused when we try to look at the background details and the background fails to come into focus.

So how do you avoid that 3D headache? Teach your brain to unlearn your experience with 2D movies and stay focused to the in-focus action. When watching a 3D movie, whatever is right in front of you and in-focus is what you want to be paying attention to—focusing on the background details for too long triggers headaches and disorientation.

Thanks Shadowlocked!