How long has this been going on? If not for long, then you could have a stuffy nose! When there are boogers (teehee, I'm such a child) trapped up there, it makes it harder to breathe, which is why you would breathe heavily. Just like a snore, it can make a whistling sound as you breathe in and out. It's happened to me before and usually happens when I have a cold or in the middle of a stuffy night.
If it's been going on for a long time, I don't think it's a danger, but if it's really bothering you, then go ahead and ask your doctor. If it bothers you and distracts you when you breathe, then I can see how that could be extremely annoying. So yes, ask him.
But if it has only been a short while, relax. It will go away in a few days. ^_^
Caitlin
its been for around 6 months, the things is it leads to a really dry mouth and people sitting next to me in lectures ask why i breathe so heavy witha wheezing noise