For a fuller perspective on what my thoughts are on geek macho bullshit, you might care to read: http://bubs.co/if-you-ever-feel-alone-in-this (I agree that there is too much of it.)

And I should know better than to post any kind of general analogy as a way to illustrate a story here on HN with a bunch of smart people who'll punch holes in the technical impracticalities of such analogy... but yes, I took a negative word of "tired" and bent it to tell a story. Rest is important. Operating at 50% isn't good for the long haul.

I wasn't trying to suggest that being tired in a way that affects ongoing abilities to perform is a good thing. I just wanted to point out that if you just pop your head in to take a measurement of something, without the context of everything else going on, then that measurement might be off... ie, the investor seeing me as tired, without knowing it was because of the intensely productive and long week I had just come out of.