(This isn't my memory. Like all my recent posts it's one of Seven Answers).
I can remember waking up in my cot and wanting people to come. But they were all still asleep [...], even my sister who slept in a bed, so I stood up by holding onto the wooden white painted rails and boinged my Humpty Dumpty up and down with the hand I wasn't holding on with.
After a long time my mum or dad would come and let me out, or my sister would get out of her bed and come over to chat and play. I don't think she was able to open the cot front and release me.
I still have the Humpty Dumpty, he is Chad Valley, about the size of a big Easter egg and made of very faded and worn pink and blue velvet. The elastic for boinging him up and down tore off a few decades ago.