In some cases it makes sense to install upgrades of packages automatically. This can reduce time for maintenance a lot. To do so, install the little helpers unattended-upgrades and apt-listchanges with the following command:

$ apt install unattended-upgrades apt-listchanges

Now make sure to set the following entries in the configuration file. This way the result of the upgrade process is sent to root's inbox. We further configure to reboot automatically at 02:00 if upgrades require a restart.

# /etc/apt/apt.conf.d/50unattended-upgrades
Unattended-Upgrade::Mail "root";
Unattended-Upgrade::Automatic-Reboot "true";
Unattended-Upgrade::Automatic-Reboot-Time "02:00";

We should also configure crontab to send a notification once the system rebooted successfully. This way we can make sure that both upgrading and rebooting were successful.

# crontab -e
@reboot echo "Subject: Rebooted at $(date -Iseconds)" | /usr/sbin/sendmail root