To disable the option of your device turn off the monitor and go to sleep after an amount of time, you can follow the steps below:

Edit the “/etc/lightdm/lightdm.conf” file adding the following lines to the [SeatDefaults] section:

 # don't sleep the screen
 xserver-command=X -s 0 dpms

Tip: To edit the file you can use the nano software by typing the following on the linux terminal:

 sudo nano /etc/lightdm/lightdm.conf

Note: This solution was tested with Raspberry Pi