Earlier quoted context omitted.
Fair enough, but just to be clear, these were the first five employees (including my cofounder and me). Now, some of us still work those hours, and some don't. We don't "monitor" hours or tell people they can't take time off or leave early - and a lot of people take full liberty to do so (and they should). Some of our employees have kids and leave earlier, put the kids to bed, and hop on IRC to help out if/when they…
You need to take some time off and go look at modern research on productivity. You're not gaining anything with these hours. You feel like you're getting more done, but the science simply doesn't support that this is what's happening.
This is the most succinct and (IMO) valid criticism of the long-hours apologias. It's not just a question of no additional productivity, but one of actual damage.
My own role[1] doubly exposes me to these risks. As I might actually handle hardware, the increased risk of "industrial" injury one exposure, and, of course, being on call is the other.
Even with the knowledge and acceptance of such studies, there's the difficult task of self-discipline. The temptation to stay just a little longer, to get one last thing working, is strong on its own, but, combined with peer pressure, is nearly irresistible. This is why it's so important that founders, managers, or anyone with a voice of authority, make[3] this an explicit part of the culture.
[1] System administration, which, for a startup at an early enough stage means anything from facilities/rack'n'stack/cabling[2] to fixing bugs.
[2] Protip: never, ever crimp your own ethernet patch cables. If they're under 20 feet, they're under $3 online (my preferred vendor is pchcables.com, due to their broad color selection). Between the cable, modular connectors (you know there are different ones for solid and stranded, right?), anti-snag boots, and amortized cost of a crimper, you might not even be saving money if labor were free. Over 20 feet, terminate both ends with a female punch-down connector (patch panel or keystone jack in a box). Never having to troubleshoot intermitted network issues: priceless.
[3] subjunctive