I can sleep good for a couple months, then for some reason the no sleep times come.  Don't snore, or have breathing problems, its right before Im ready to sleep it seems my blood turns on fire..... gotta get up and move around, wide awake.... Then crabby the next day.  Am sure some of the tone of my posts here relates to those times also.

Google:  food for sleep.   Theres allot of food that will make you more apt to sleep, and more to stay awake.

Helps me.

Glad your surgery was successful, it could be you just need more time to get normal sleep pattern.  2-3 months to me seems like forever, but in the grand scheme of things isn't very long. 

Im just a farmer, so take this advise for what ya paid.