Seriously though, do you yourself going onto the same websites over and over again, every hour or maybe more often than that? Set a schedule so you only check news and social sites every couple of hours at most, and then just for a few minutes. Easiest way is to synchronize with your normal ‘break’ rituals like coffee, lunch, stretching, etc.
Chrome has an extension called StayFocusd which can help you limit your browsing time, and Firefox has one called LeechBlock which does the same. If you use Safari you can try WasteNoTime.