What’s Going On in Your Body When You Watch a Horror Movie

Your casual denial and nervous laughter might fool someone else into thinking you weren't really scared, but you can't fool your heart. That's been confirmed by a joint university study published in the medical journal Circulation, Arrhythmia and Electrophysiology (via University College London). When volunteers were shown scary film clips, researchers found there was a very definite change in blood pressure, heartbeat, and even in the cardiac muscles.