The irony of this increase in working hours is that it usually comes in service of extraordinarily bad ideas, the majority of which end in failure.
A study in Sleep, the journal of the American Sleep Disorders Association, found significant declines on "divergent" thinking, a category of mostly creative brain functions.
Sounds a bit like Modafinil's effect on me then.
Here's a constructive and effortless suggestion if you want to easily boost your startup's success chances by what, in my opinion and experience, will be a significant margin (more than double I reckon):
Sleep 8 hours a night minimum, and enforce a half-hour walk through a park every day. And a two-hour walk on Sunday.
Your best ideas will come during that walk, and they will make a very tangible difference to your business's likelihood of success.