A new Google Chrome extension "Focusbook" is here to tell you why you opened Facebook. The clever plugin prompts users to avoid spending excessive time on Facebook, reminding them to use it - and their time - more wisely."Focusbook helps you stay productive on Facebook. When you first open it, it will request that you specify a goal, and it will remind of that goal periodically until you close Facebook," Chrome says on its website. When you open Facebook the plug-in will ask you to specify a reason such as "searching for someone," "messaging" or "wishing a friend a happy birthday." After a while, Focusbook will continue to ask whether you have completed your task or not with pop-ups and a transparent blue mist until you accomplish it.Chrome's latest extension is rather annoying but aims to make users aware of their Facebook addiction, which has become a wide source of concern. A study by California State University has recently found that scrolling through one's Facebook feed may affect the brain in somewhat the same manner as using cocaine. An earlier study conducted at the Copenhagen-based Happiness Research Institute last year also demonstrated that Facebook users are less happy than those who do not use it. Those who did not use Facebook report feeling happier, more emotionally balanced and better able to concentrate.