Could be your adenoids.
I had mine out a few years back and now I sleep much better. Mine were really big and blocked my nasal passage so I only could breathe through my mouth. I had enlarged tonsils too so they took those out too and also performed a turbineectomy (sp) - essentially channeled the inside of my nose by 3cm to open up the passages a bit more.
Get it checked out, the above has helped me absoloutely loads. I now don't snore and sleep all the way through the night as well as not choking in my sleep (used to happen 3 times a week, essentially died due to my throat collapsing).