prevent debian from sleeping

[Jack Dangler <tdldev@gmail.com>]

Hi, all - 
Just noticed that my deb sessions are going to sleep. I setup
my .xinitrc file to prevent it using xset, but no joy.

The .xinitrc contains the following - 
xset s off	# don't activate screensaver
xset -dpms	# disable DPMS (energy star) features
xset s noblank	# don't blank the video device

exec /etc/alternatives/x-session-manager # start lxde

after adding the information here, i rebooted the system, but no change
in the behavior. Any suggestions about how I can eliminate this behavior
when it is not wanted (i.e. i'm watching a long video on youtube, or
attending an online class, etc.).