The Darkened Screen
Ubuntu Linux is configured out-of-the-box with aggressive power-saving settings, primarily to extend the battery life of laptops. One of the most noticeable features is the automatic screen suspend (or screen blanking). If you do not touch your mouse or keyboard for a relatively short period (usually 5 minutes), Ubuntu will automatically dim your screen to black to save power. While excellent for a laptop running on battery, this is highly disruptive if you are using a desktop PC to monitor a long-running terminal script, read a lengthy PDF without scrolling, or use a second monitor as a permanent dashboard display.
Disabling Screen Blanking
To keep your display constantly active and stop Ubuntu from automatically suspending or blanking the screen due to inactivity, you must adjust the system’s power management timers.
Click the system menu in the top-right corner of the Ubuntu top bar (where the volume and network icons are) and select Settings. In the left-hand navigation sidebar, locate and click on Power (on some older Ubuntu versions, this setting might be found under ‘Privacy’ > ‘Screen Lock’ or ‘Brightness & Lock’). In the main Power panel, look for the section labelled “Power Saving Options.” You will find a dropdown menu specifically named Blank Screen (or ‘Turn off screen when inactive for’). Click this dropdown menu. The default is likely set to 5 minutes. Change this setting to Never. Your Ubuntu monitor will now remain brightly lit indefinitely until you manually lock the system or turn the physical monitor off.