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.