It felt like I was awake, couldn't move, and someone was in the room, then it would feel like you were being grabbed and you'd wake up freaking out. The first time it happened I thought I was actually being robbed and the people in the room either didn't see me under the sheets or thought I was asleep, then when that grabbing sensation happened I thought it was because I moved too much and they noticed so I was about to fight. It's far less frightening when you know what to expect.