The smart way to work a 12-hour day

(MoneyWatch) The 40-hour workweek has been getting a lot of attention lately. Bob Rosner's The Boss's Survival Guide advocates working less to boost productivity; Sara Robinson's recent AlterNet article on the 40-hour workweek has been shared far and wide. We all have a point of diminishing returns. From studying my own time logs, I see that mine is somewhere between 45-50 hours a week, which when you average in vacation days, half days and the like, probably comes out to a yearly average of around 40 hours per week.

But still, to hit that average of 40 hours -- or because you are personally invested in a project and enjoy it -- you sometimes need to work long days. Is there a way to work a 12-hour day and still be productive through most of that? And, bonus question, is there a way to still have a personal life on that 12-hour day?

I think the answer is yes. You just have to employ a little trick that high-mileage runners know, and that many people discover when they become parents: You split your shifts.

People trying to up their running mileage figure out that there are two ways to run 12 miles in a day. You can run all 12 at once and get it over with. Or you can split that into two runs, say 9 miles and 3 miles. This will take more time overall (there are transaction costs to starting up any activity in terms of time and energy). But it's often psychologically easier to face two shorter runs rather than one longer one. Indeed, after running 9 miles, running 3 miles almost seems like nothing.

Likewise, when many people become parents, they suddenly realize that their formal workday does have to end. A child has to be picked up at daycare at a certain time, or a nanny needs to leave or your spouse will threaten to leave you if you don't get home to help with the baby during her fussy time. So even if everything isn't done, you stop. But then, after your children go to bed, you fire up the computer and get back to what you were doing.

That latter situation pretty much describes my life. I have childcare until 6 p.m., and out of respect to my sitter and desire to see my kids, that is when I stop. I am never actually done at 6 p.m. But I'm ready for a change of pace. So I hang out with the kids, eat, relax, and get them to bed. At 9 p.m., the house is quiet. And it's back to my home office for another shift, with renewed energy. I can often crank things out until I run out of steam at 10:30 or 11 so. I know that if I worked straight through until 8 p.m., I would have a hard time getting as much done. By carving out three hours in the evening for a family and personal life, I can wring the most work out of those late night hours.

The downside? I don't watch TV. But if you don't view losing out on TV time as a huge downside, then maybe splitting some shifts could work for you too.

When do you fit in extra work hours?