Why does my mouth fall open when I sleep?
Patient: When I sleep my jaw falls open. I never used to happen, only about 3 weeks ago it started. It causes me to wake up in the night to close my mouth. It doesn't appear that I am breathing out of my mouth when it opens. What can I do about it? Is it because of weak muscles? Can this be fixed? Doctor: Hello. Welcome to Healthcaremagic.com,   There are many reasons that during sleep mouth opens. 1) There may be the blockage in nasal passage because of recent cold or sinusitis. 2)  Second thing is obesity, if you are little over weighted. 3) Improper sleep, upside or downside facing during sleep. 4) Maloculusion, upper and lower jaws does not fit properly.   You must check which one is there in your case and you will get rid of that.  Thanks for the query...... Regards........