At first, the author thought he was having a stroke. Then she finds out a bizarre sleep disorder is more common than she ever imagined, reports Narratively.

Most nights, thankfully, the meditation app helped me calm down enough to drift off while listening to it. That was the case this night, and I was grateful when I was able to turn off my phone and still feel myself fading. But just as I was about to be out, I heard a tremendously loud crack. My eyes flew open and I sat up in bed. It sounded like a gunshot, and my mind raced: I’ve never heard of gun crime in our neighborhood. I guess that doesn’t rule it out? But after a few seconds of panic, I realized I hadn’t really heard the sound. At least not in the typical way we hear sounds; the sound had come from inside my own head.