Anecdata. You forgot Margaret Thatcher (4 hour nights).
The article also pointed to a counterexample - Albert Einstein (10 hour nights).
Anecdotes are not sufficient to prove either point, you should look at the research on this. And research shows[1] that animals that are sleep deprived perform significantly worse in cognitive tasks.
Now, when humans start being "sleep deprived" will vary among individuals - but at least 6 hours is definitely required in most of us (of course, exceptions to every rule.)
Obviously, (as I am sure you are aware after careful consideration of my argument) my conclusions were towards the need for a better understanding of the subject itself and not towards "proving" a particular subjective viewpoint on the matter.
I thought it fair though to offer up symmetrical counterpoints to the OP to show that this is all drawing global conclusions on a particular set of examples (or small sample sizes if you will).
> An abundance of scientific findings, many from research sponsored by the military and NASA, has led many executives to abandon the quest to minimize sleep unreasonably.
They aren't arguing entirely from anecdotes, they are using them to illustrate the point mostly. They are writing for a broad audience of non-scientists, which they've used as an excuse to exclude references from passages like the above, perhaps justifiably.
Ah, but we would need to know the parameters and conclusions of these studies to know if the author was utulizing the data and findings correctly or if he is using it in a biased manner.
Assuming, he references the generality of the studies appropriately (abandon the quest to minimize sleep unreasonably). Then the discussion should cater towards the differences between unreasonable sleep deprivation expectations brought on unwillingly and its toll on the mind vs. sleep deprivation willingly done due to a personal will to finish a project or continue a streak of creativity, etc.
If you want to know, raise some funding and do a meta-study. This was just an article to provoke thought among business-types (being in the Harvard Business Review) - If you want to find The Truth then you can, the universe is right there in front of you to measure.
(I'm only half joking - if you put a proposal for a meta-study about this research up on Kickstarter, I will back it.)
The article also pointed to a counterexample - Albert Einstein (10 hour nights).
Anecdotes are not sufficient to prove either point, you should look at the research on this. And research shows[1] that animals that are sleep deprived perform significantly worse in cognitive tasks.
Now, when humans start being "sleep deprived" will vary among individuals - but at least 6 hours is definitely required in most of us (of course, exceptions to every rule.)
[1] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2982737/