laptop screen question
 

I've had my laptop for a few years now, but didn't really start using it until about 6 months ago (use it everynight now whereas before it might have only been maybe 4 times a month).

Well sometimes it is like the screen is flickering and it is really annoying. It's not bad, it's just like it get light and dark, kind of like what a flourescent light does when it starts to go bad.

Anyone know what could be the problem?