You sleep on a hard surface? That is really difficult for me as a side sleeper. I have slept on hard surfaces out of necessity and my hips and knees are hurting by morning. Do you use a pillow or is your head on the hard surface too?
I was a restless sleeper though and had/have extreme difficulty getting to sleep often; learning to sleep on my back helps. Expressed another way, if my brain says I have to be on my side for comfort, and I have to achieve comfort to sleep, then if that comfort isn't achieved no sleep for me. Getting my brain to accept "and now we lie down for sleep" without thinking about comfort let me be actually comfortable in more positions/settings.