If you had an out of body experience how do you know it was real and not a dream?

If you had an out of body experience how would you know you did not dream it? Say you were at work and some object dropped on you or you were in a car accident, if you had a vision that seem pretty real where you were somewhere else or with loved ones departed that seems so real but then you “came back” to discovered you were in the ER, in recovery, or on your back being worked on by the paramedics, how would you know as real as the experience was you were not just dreaming it?