Why do people snore while sleeping?

I think snoring is caused of stress and you had your mouth open while sleeping.

Improper positions while sleep is the cause ( …my think

Tiredness

Stress is a factor, some hereditry, airway obstruction.

Snoring occurs when the tissues in the upper airway vibrate as air passes through them during sleep. This vibration produces a snoring sound. 

Block airways due to fat or stress.

You may want to try, if you haven’t already, purchasing a snoring pillow or try over the counter nasal strips that can help to open up your airways.

I’ll just add this. Maybe it will help you. Sleeping on your side can help reduce snoring or on your back with a pillow wedge elevating your upper body. I have to use the pillow wedge because I can’t sleep on my side anymore.

I think there could be many reasons. I snore sometimes when I lay a certain way because I have a deviated septum or when I am severely sleep deprived. I have trouble with insomnia which is an off and on problem for me. The main cause of this is usually airway obstruction. My dad has the same problem but his was worse. He snored every night.