If you reading this online at work - in between checking emails, writing a report for your boss or a client and/or monitoring the price of tea in China - you're risking a major drop in productivity. Hopefully the time you're spending away from other tasks will be balanced by learning something new and interesting. But even if it's relevant to your work, switching back and forth between screens can seriously mess with your mind. According to US media and technology writer William Powers "...we're constantly contending with far more tasks than our minds can handle. We find it increasingly hard to concentrate on any one of them for more than a few minutes. It's estimated that unnecessary interruptions and consequent recovery time now eat up an average of 28 per cent of the working day".