sounds like youve got a heavy blanket/duvet i used to do that, id wake up under my duvet boilin hot.. i used to crawl down into it though, so after breathing for an hour, it gets all stuffy and i wake up nearly suffocating, i used to just throw my duvet away.. and sleep in trakkies (tracksuit bottoms) it always did the trick for me...

good luck, i know how shit that can be...