When i leave the game the game runs by itself and causing me to die

Whenever i am offline for some reason the game always runs by itself then causing night time to come and then causing me to die ingame which is very frustrating when i built something in survival then i leave and come back it says Respawn or main menu and then i see i was killed by a mob please i dont really know why but my only thought of this happening is the game runs by itself,im sorry for not that detailed information but this is only what i know.Thanks for understanding