The Aggressive Power Saver
Ubuntu’s GNOME desktop environment includes aggressive power-saving features designed to maximize laptop battery life. One of the most noticeable is the automatic screen dimming. If you do not touch the mouse or keyboard for a few minutes, Ubuntu will gradually dim the display backlight to conserve energy before eventually turning the screen off completely (blanking). While this is excellent for battery management, it is incredibly annoying if you are using your computer to read a long article, reference a coding tutorial on a secondary monitor, or watch a video in an application that doesn’t properly inhibit the power management daemon, forcing you to constantly wiggle the mouse to keep the screen bright.
Disabling Screen Dimming in Settings
To maintain a consistent brightness level during passive use and stop Ubuntu from automatically dimming the screen when you are reading or watching, you must adjust the GNOME power settings.
Click on the system menu in the top-right corner of the top bar (where the battery, Wi-Fi, and volume icons are located) and select Settings from the drop-down menu. In the left-hand sidebar of the Settings window, scroll down and click on Power. Look for the “Power Saving Options” section. Here, you will find a toggle switch labeled Dim Screen When Inactive. Click this toggle to switch it to the Off position. While you are in this menu, you may also want to adjust the Screen Blank setting (located just below) to a longer duration (like 15 minutes) or “Never,” to ensure the screen doesn’t abruptly turn off entirely while you are reading.