Macbook Pro screen goes black for a second in the middle of using.?

I have a Macbook Pro from early 2011, (with OS X) and recently, the screen has started going black just for a second, and then to return to what I was doing before. It's just like I put it to sleep but wake it up again after a second. It only does this when it's running on battery, but the battery level is never actually low. It happens when I'm using it, and then when it returns to normal nothing has changed, nothing is missing, has closed or anything. Is there anything I can do or do I have to go get it checked out? Thank you for any help, would prefer to keep this computer for a lot longer :P