According to current neuroscience research, after focusing intently on a project or problem, the brain needs to fully disengage and relax. As composer, musician and producer Brian Eno has opined: “The difficulty of always feeling that you ought to be doing something is that you tend to undervalue the times when you’re apparently doing nothing, and those are very important times. It’s the time when things get sorted out. If you’re constantly awake work-wise you don’t allow that to happen.” More pithily, as said by John Cleese: “If you are racing around all day, ticking things off lists, looking at your watch, making phone calls, and generally just keeping all the balls in the air, you are not going to have any creative ideas.”
From Go Ahead, Take That Break over at The HBR blogs, often a good source of work related inspiration.