[GTALUG] Keep X from going to sleep

Here's a problem I'm hoping to solve: When idle for some amount of time, X shuts down the screen. When a program like VLC is playing a video (or even paused) this does not happen. How can I tell X to never sleep? I just want it to send output down that cable, constantly, forever. I manage screen burn and power wasting by turning off the monitor, but when the screen goes to sleep, my inexpensive monitor (an LG) sometimes has trouble noticing and won't display anything until X is restarted, which is a pain. Thanks! PS The system is Debian testing.