Have you found yourself to be unproductive, too edgy, unable to focus on even the smallest things, well, that means that you are stressed. You've driven yourself to an uncomfortable state where your brain is "out of its zone".
So take a day off, maybe two.
And follow the next few actions to get back in a comfortable zone:
Disconnect: Turn off cell phones, Blackberry and iPhones, email pings, rings, social networks, PCs, TV, etc. Anything that is intrusive to your silent mental space.
Deep Breathing: Seat yourself with your feet crossed, your back straight, close your eyes, and just breathe. Do this in 30-breath series, increasing intensity on the first 10 series, and decreasing breath on the next 20 series.
Take a walk: Go to a nearby park, better yet, to a forest outside the city and take a LONG walk. I mean 1-hour+. Preferably alone (just make sure you are in a safe area with other people walking around there). No iPod or other gizmo in your ears. While walking, repeat those breathing exercise from above.
Read: Take a book with you, a pleasant one. Read. Listen to yourself "dream" while you're awake by following the story. This will take you away from the stressful thoughts that brought you in the stressful state in the first place.
Take a nap: Go back home, and take a nap. Not in your bed, otherwise your mind will think it's bedtime.
After a day like this, you should feel rejuvenated mentally. Making you feel you've gone back to your "roots" as a human being, rather than an auto-piloted constantly-connected robot.