I have the same advise as the ladies above. Def go to the doc and ask for a referal for a sleep study to be done.
I have had a couple of friends with similar issues. One of them was told the results of the sleep study where fine and as long as her son was acting normally the next day he and wasn't over tired then he wasn't being affected by it (her was older -about 8) but the other family (like was mentioned above) had to have their daughters tonsils/adenoids taken out to stop it.

Good luck