This is what MS calls "quiet time". During the time period you mention, MS updates are download and installed without interrupting your daily PC activity. It's a good feature of Windows 10, it saves you from the hassle of having to save your work in progress, close all running programs and perform a PC restart so Windows can configure and install the new updates. I believe you have the option of selecting a time to install updates at a more convenient time. Maybe when your sleeping LOL
Click on Start > Settings > Update and Security > Windows Update near the bottom of the page you will see "Select a more convenient time to install updates" My setting is 03:30.
this isn't right, i have other windows 10 computers that aren't rebooting EVERY single night. There is no way microsoft is pushing daily updates that require reboots every night. Something else is wrong
Easily done, easily undone.
Basically you're just disabling all the Startup Items and All non-Microsoft services.
Be sure to check the box to hide Microsoft Services, as you don't want to accidentally disable any of those.
Run it like that for a day or two and see if the problem persists.