Where is that sound coming from?
Snoring occurs because your muscles relax when you sleep. This includes the muscles in your tongue and palate. As a result, your airway narrows when you breathe in and open your mouth. The air travelling through the narrowed airway makes the uvula, mouth, and throat vibrate, which results in snoring.
This constriction can have several causes, such as the tongue and the uvula sliding backwards when you lie on your back. But it can also be caused by irritation of the respiratory tract or, if you are unlucky, by genetic predisposition.
Bad habits such as excessive alcohol consumption and smoking make snoring worse, and unfortunately the risk of snoring is even higher if you are overweight.