I leave my PC running 24/7, with only the occasional and require reboots.
For some time now, I have found that windows does not come to life when I have left it unattended for several hours, and I have to restart it. This is annoying as I have some software running continually which needs access to the outside world if you like. Actually it gets data from a external weather station, and if it can't then I have to wait while it gets updated as soon as I restart windows.
My settings are 'Never turn off the Display', as I do that, and 'Never put the computer to sleep' because I don't want it that way.
I save the settings, and a couple of hours later, or after a reboot, I recheck, and they have been changed back to Turn off Display 1 hour, and Put Computer to sleep after 1 Hour, regardless of me saving the changes I made.