How to disable sleeping on Raspberry pi

You don't need to install lib, just edit lightdm

1 - Open lightdm using your prefer text editor, eg using default editor(nano).:

sudo nano /etc/lightdm/lightdm.conf

2 - Add this line

xserver-command=X -s 0 -p 0 -dpms

I recently installed Raspian Buster with Desktop (circa 2019-September) - the smaller install with the Desktop, but without the "recommended software". I found there are two settings that have to be changed as either one of them will blank the screen in ten minutes under the default settings.
set screen saver timeout to zero:

xset s 0

and set dpms (EnergyStar) to disabled:

xset -dpms

This way I haven't needed to install anything (no screensaver). It was confusing because I'd tried both items, but it wasn't until I learned they both were blanking the screen at ten minutes that I saw what was going on.
As this has tested out OK, the next step for me is to put them into an autostart routine.
ps Verify your settings with

xset q

Without installing anything, official Raspberry Pi doc:

On the ConsoleIf you are using the Raspberry Pi solely on the console (no desktop GUI), you need to set the console blanking. The current setting, in seconds, can be displayed using

cat /sys/module/kernel/parameters/consoleblank

Here, consoleblank is a kernel parameter. In order to be permanently set, it needs to be defined on the kernel command line.

sudo nano /boot/cmdline.txt

Add consoleblank=0 to turn screen blanking off completely, or edit it to set the number of seconds of inactivity before the console will blank. Note the kernel command line must be a single line of text.

https://www.raspberrypi.org/documentation/configuration/screensaver.md

Simply enter the config with sudo raspi-config and disable screen blanking in the display settings.

I've created a picture frame with a pi 3 and want to stop the screen going blank. I installed xscreensaver as in answer 22 and it's working a treat:

sudo apt-get install xscreensaver

After install, went to Rpi's desktop "Menu" (left top corner)

Went to preference ---> screensaver.

Then In mode : section, selected "disable screensaver" and closed.

Rebooted Rpi.

I had the same issue with Raspbian OS that was installed on raspberry Pi device. I just installed xscreensaver by using the following command in default Command panel.

sudo apt-get install xscreensaver

After installation is completed, Go to the menu in the left corner and select preference. First time you will see a pop up to enable xscreensaver on your screen. Just accept it. After that you can disable the screensaver.