I recently installed Gnome Shell 3.20.4 and desktop on top of an fresh Ubuntu 16.04.3 installation. Now, I want my monitor to go to sleep after 1 minute of inactivity ("blank screen"). That configuration works fine on Unity, the screen will dim after 45 seconds and the the display turns off. On Gnome the screen will dim at 45 seconds but at exactly 1 minutes brightness goes back to normal and the display never turns off. What can I do? I already reconfigure everything on Gnome settings. It is like something is waking up the system just before the display turns off. Thank you!!