My scarf stays on at night. It's 34" x 34". I bought it from tenderheaded.com.
When I tie it I lay the scarf over my head so that 2 corners of the scarf are at my shoulders, 1 corner is at the center of my back, and 1 corner is in the middle of my chest. I take the side corners and tie them in the back in a double knot. I leave the back corner hanging down. I pull the front corner up so that I can see, but I keep the scarf low on my forehead, just above my eyebrows. It doesn't come off when I'm sleeping. I hope that helped. I don't have pictures.