I work 168 hours per week. I don't spend all of those hours sitting in front of a keyboard; I don't spend all of those hours consciously thinking about what I'm doing; for that matter, I'm obviously not even awake for all of those hours.
But at some subconscious level, I'm always thinking about work -- even when I'm sleeping. I've lost count of the number of times when the solution to a problem has come to me in a dream.
You're not really answering the question in the spirit it was asked. At the very least I don't think you should count the time you spend on YC News as work (unless you're actually pg or your work somehow relates to it).
I'm appreciative of the answer though, because it raises a distinction between work in an aesthetic, at your desk between the appropriate hours and dressed professionally sense, and work in the sense of really thinking about and solving outstanding problems, and formulating new ideas. These two time periods are not mutually inclusive, and can be mutual exclusive depending on the environment in which one works.
But at some subconscious level, I'm always thinking about work -- even when I'm sleeping. I've lost count of the number of times when the solution to a problem has come to me in a dream.