Last night I was in my flu, woke up during midnight, listened to sermons. Towards a half-sleep half-awake state, my spirit heard the sound of a shaker coming from my bedroom closet. After the whole incident was over I knew it was a spiritual sound, simply because there was no one in my closet. The sound continued for a little while, I just knew a spirit was in there making that sound. Then I felt this spirit being, probably a demon, coming onto me and try to oppress me. These "oppressing" incidents have happened to me a few times, but mostly before coming to know Christ. After being saved, they don't usually happen, and sometimes they would just disappear after I keep uttering the word "Jesus."
I knew there is also a physical phenomenon of a similar kind, called a sleep paralysis, which I could differentiate. When I'm especially very tired, the head may sometimes "wake up" first while the body is still in a "sleep state," so it feels like one could not move the body but awake. In this case, it's not a spiritual demonic act, but a biological condition.