In 1998, Carol Weihrer was undergoing eye surgery when she woke up. Desperate and in agony, she could feel everything that was happening to her, but the muscle relaxants kept her from moving or speaking.

This happens to 4,000 people each year, largely due to anesthesiologists’ errors, and the psychological trauma can lead to years of nightmares, flashbacks, insomnia, and alcoholism. It’s called “anesthesia awareness.”