It takes some time for the tissues around the operation site to calm down. I had to sleep sitting up for 2 weeks after my Op.
Patience and not overdoing it is required, along with the right pain killers at the right time.
You will start to gradually feel better, its not an overnight recovery. After my ACDF the only way I could get comfortable to sleep was by placing my pillow under my lower back with my head flat against the mattress.Narcotics also played a big role in recovery as well.One step at a time and you will get there.