Why is my sleep/wake screen has this light only in the center?

Sometimes when you open a macbook it has this dark screen where it happens when you press the button to make it deem the most. But then, even if, I didn't deemed my screen sometimes when you open your macbook it's selected to the deemest screen and can not make it brighter. And so, I use to just close and open again and then it works fine.

However, I just got this another problem, where first, when I close my laptop it makes this CD ROM turning sound constantly, then now, when the mac is in the deemest mode, only center is bright enough to see but the other sides are totally turned off or too dark to see anything. I just want to know what's going on with my macbook.