Is there a command line prompt to disable sleep? Or is there a file I can access on the Raspberry Pi to change?
Force the screen to stay on:
From an SSH session in PuttySSH or a terminal session on the Raspberry Pi itself:
$ sudo nano /etc/lightdm/lightdm.conf
Add the following lines to the [SeatDefaults] section:
# don't sleep the screen xserver-command=X -s 0 dpms
CTRL+x to exit, Y to save then enter to accept the filename