I had one sleep paralysis episode where a silhouette of a person was standing next to my bed holding me down, and I was positive they were going to kill me. In another, creatures were crawling up the walls and across the ceiling trying to get at me. A third episode had me falling downwards as though I was falling through the earth, and I felt like I was vanishing. They can be pretty frightening.

When do you usually experience it? In the morning, when trying to fall asleep, or some time during the night?

Why I ask is because depending on when you experience it, it would likely be due to when you're waking up. If you wake up without that particular sleep cycle completing sleep paralysis becomes much more likely to occur. I used to try to make it happen by timing an alarm clock to hit my REM sleep. The reason I did that was because it can be easy to launch into lucid dreams from sleep paralysis.