I see that unattended-upgrades issues
shutdown -r command with the scheduled time. However, the PC is sleeping at that time. It also doesn't restart after manual wakeup. This is for a computer novice user (grandma), she most certainly forgets to restart it every week or so. And i don't want to restart it immediately to avoid interrupting her work, so decided to do it in the middle of the night.
UPDATE: Grandma wakes the PC from sleep with some random button, most certainly the power button.