Snoring and dry

My father, 48, has been snoring for several years now.  Heavy snoring.  He wakes up in the morning and drinks a tall glass of water because he is so dry that he cant even talk or swallow.  Also I notice that he has some nose issues.  I notice it only when he eats.  You can almost hear him breath out loud.  Also, last month he had a short period where he felt dizzy for 2 days.  My Mom thinks it could just be related to stress and not his nose.  I think he has issues with his nose and not getting enough oxygen.  What could this be.
thank you