Not long ago, information overload was the bane of office life - a deluge of data inundating our workstations and destroying our collective productivity. Then we discovered that so much information on the internet was rubbish and that we could safely ignore any e-mail addressed to more than three people. Now, though, there is a new workplace affliction: interruption overload.

People used to be able to interrupt you at work only by phoning or walking into your office. Now they can do so by e-mail, instant messaging, mobile phones (with voice calls and text messages) and BlackBerries or personal digital assistants.