Have a close look at your breathing pattern, do you breath through your mouth or your nose or a combination of both? Much sleep apnea is due to mouth breathing particularly at night. Buteyko exercises has a significant effect on sleep apnea.
Ask someone to watch your mouth and tell you to shut it when they observe you mouth breathing. A simple test for nose function is: Can you fill your lungs as quickly through your nose as through your mouth? If you cannot your nasal passages are blocked because of your mouth breathing. To open up your nasal passages breathe through them. Don't mouth breathe.