Even the 8 hr work day doesn't work well for folks like yourself. There's always an exception to the "norm".
When I was self employed in the Computer biz I would often put in 16 hour days, 7 days a week. Mind you, I made a lot more money than I do now at a job that's 8 hrs a day, 5 days a week. Main difference now is I get to enjoy a life outside of work, I'm virtually stress-free, and healthier.