I awake some mornings with an extremely painful tongue. it is just the top that hurts. there is nothing out of the ordinary looking at my tongue.

Burning tongue: A painful tongue can be the result of dry mouth. If you are breathing through your mouth while you sleep the dryness can cause a burning sensation of the tongue. Try using biotene gel to coat your tongue when you go to sleep and see if this helps. If not, have your dentist or ENT check it to be sure there isn't another underlying cause.