How to Change Screen Timeout and Automatic Suspend Settings in Ubuntu

Leaving an Ubuntu laptop or desktop PC unattended should ideally conserve electrical power and protect privacy without interrupting long downloads, compile tasks, or media presentations. However, default Ubuntu power profiles may blank your monitor too quickly while reading long articles or put your computer into deep system sleep during background file transfers. Customising screen blanking delays and automatic suspend timers ensures your workstation remains responsive when needed and energy-efficient when idle.

Configuring Screen Blanking (Display Timeout) in Settings

Screen blanking turns off monitor backlights after a period of user inactivity without putting the system into sleep mode:

1. Open the Settings app from the application grid or top-right system status panel.
2. In the left sidebar, click on Power.
3. Locate the Power Saving Options section.
4. Click on Screen Blank.
5. Choose your preferred idle timeout from the dropdown menu (options range from 1 minute to 15 minutes, or select Never to prevent the screen from ever turning off automatically).
6. The monitor will now respect your new timeout duration before powering down backlights.

Configuring Automatic Suspend (System Sleep)

Automatic Suspend puts your entire computer (CPU, RAM, and fans) into a low-power sleep state:

1. Under the same Power settings menu, locate Automatic Suspend.
2. Click to open the configuration dialog.
3. On laptops, you will see independent toggles for On Battery Power and When Plugged In:
   • Set a conservative timeout (such as 15 or 20 minutes) when running on battery to preserve charge.
   • Set a longer delay (such as 60 minutes or Off) when connected to AC mains power to allow downloads to finish.
4. Toggle off the master switch if you run local file servers, media streaming, or background tasks that must never be interrupted by sleep.

Managing Automatic Screen Lock on Blanking

By default, Ubuntu locks your session and requires password re-authentication the instant the screen blanks:

1. In the Settings app, click on Privacy & Security in the left sidebar.
2. Click on Screen Lock.
3. Adjust Automatic Screen Lock Delay (e.g., set to 5 minutes after screen blank if you frequently step away for quick tea breaks).
4. Toggle off Lock Screen on Suspend if password prompts are unnecessary on a secure home desktop.

Temporarily Preventing Sleep from the Command Line

If you are running a lengthy software compilation or multi-gigabyte download and want to inhibit sleep temporarily without modifying settings:

systemd-inhibit --what=idle:sleep sleep 3600

This command prevents Ubuntu from entering idle sleep for the specified duration (3600 seconds), releasing power controls automatically once completed.