This is interesting. Found it on howstuffworks.com:
"Tracking 2,225 people around the world (funny enough, via an iPhone app called TrackYourHappiness), the statistics concluded: being present with one's task at hand-- even when it wasn't the most enjoyable-- was linked to happier, more content states of mind. Whereas wandering minds, even when it wandered to pleasant thoughts, dreams, and plans (like vacations) were ultimately less happy. Daydreamers, take note."
I think this can be a chicken and egg type of question- Are you daydreaming because something about the task at hand is depressing OR are you already depressed and so you daydream while you do the task? I find this a really interesting query. The same with being introverted/socially withdrawn. I am pretty introverted without many social contacts but is this because I dd or do I dd because I am introverted by nature and not a social butterfly?