This has only happened to me once. I was conscious, my eyes were open, and I was able to move my pinky and ring finger on my left hand. My wife sleeps to my left. I kept clawing at her, trying to scream her name, but only a sound that resembled her name came out. On the other side of the room, was a tall, dark, shadowy figure with faint, white eyes. Just staring at me. Not moving. Eventually I fell asleep and woke up in the morning.
An experience I don't care to repeat.