Probably 10 on weekdays, 3 on weekends. I would rather be outside.
o 1-3
o 4-7
o 7-10
etc
I also stand barefoot(very very important as normal footwear forces your weight over your toes, witch is bad for your knees and posture), and learnt how to stand in a right posture from books.
The first thing I do in the morning is exercise, and it really helps to boost my energy(it has to do with the lymphatic system).
It took me months to get the musculature in my legs, now in the subway I don't want to sit.
Me personally, 8-10 hrs a day for my fulltime job, usually take ~4 hrs off for super/gym/etc, then back on the computer until 2-4am. So ~14 hrs a day on weekdays. I try to stay off the computer as much as possible on the weekends to reset myself, but that doesn't always happen..
Workdays: 8-9 on work, plus 3-5 personal at home (and then about 6hrs of sleep paired with 2-4hrs of personal activity like cinema or meeting friends. A day seriously needs more hours!)
Weekends: Depends, laptop is almost always on and I just sit down, get up, sit down, but I'd say its within a 6-8hrs rate.
I love what I do and the amazing things that I see and learn in that time, but when I'm lying on my deathbed am I going to be proud that I spent literally the majority of my limited time on Earth punching buttons on a glowing box?
I usually take a 30m break to walk my dog and a 2hr gym excursion every other day. So most days I'm at my computer for 13 hrs at least :-) Got to love programming
With these numbers, I'm not considering Hulu, which is my primary source of "brain: off" entertainment.
I'd trade some of it for time with a real human being, preferably someone that feels soft :)