my phone is killing me

first, the contacts and phone app, now I've realized sometimes it restarts on it's own whenever it feels like to, WHEN I SPECIFICALLY TURNED OFF AUTOMATIC RESTARTS IN SETTINGS. and funny part is that it always happens when I'm sleep. like if stay up a whole week, it wouldn't restart. and fyi, I keep my tabs open in incognito mode and the restart really makes me wanna buy an iphone