I received an email from a colleague at 4.43am last Friday and another in the early hours of Saturday morning.
I used to respond to such emails telling him to get back to bed - albeit many hours later, so they weren't that effective.
I am now less shocked at the time stamp on his correspondence as I know he's an insomniac and, despite adapting his lifestyle and at times willing himself to sleep, he invariably finds himself awake at horrible hours.
The only upside? He gets a crazy amount of work completed while the rest of us are sleeping.
We all know colleagues who work long hours - the guys and girls who are always at their computers so you never know if they've actually gone home.
Are long hours a prerequisite for success? My insomniac friend is hugely productive and a standout performer but I'm not sure I can say that of all those in our industry who habitually work late into the night. Some work late because it's an industry norm and nobody wants to be the first to leave the office.
The work-life balance debate recently featured in a Twitter exchange between technology investor Blake Robbins, who has worked for companies like Google and SpaceX, and venture capitalist Keith Rabois, a long-time investor and employee at successful start-ups PayPal and LinkedIn.
Robbins tweeted: "When I first got into tech, I thought it was 'cool' to work on the weekends or holidays. I quickly realised that's a recipe for disaster. Not hanging with friends and family because you're working isn't cool. Burning out isn't cool.
"I promise you ... your competition isn't beating you because they are working more hours than you. It's because they're working smarter."
Rabois quickly responded: "Totally false. Read a bio of Elon Musk. Or about Amazon. Or about the first four years of Facebook or PayPal. It is pure arrogance to believe you can outsmart other talented people."
Rabois is at the extreme end of the 'hard work camp'. In a Stanford University class on start-up companies, he posted a slide quoting NFL coach Bill Walsh: "How to tell if you're doing the job: If you're up at 3am every night, have a knot in your stomach, a rash on your skin and you're losing touch with your wife and kids."
Rabois concluded: "If this doesn't sound appetising, you probably shouldn't start a company."
At the other end of the debate are psychologists who point to the 'labour illusion'; it says people routinely confuse effort with results - to the point where effort is over-appreciated relative to the actual outcome.
Psychology writer Oliver Burkeman says, contrary to the thinking that a jammed schedule equates to high productivity, it has been very well demonstrated that in certain fields - particularly those requiring creativity - less "work" can actually lead to more value.
There is, I think, a middle ground. Work hard - harder than your competitors - but don't go crazy.
Mathematician Richard Hamming once lectured on how people can do great work, "Nobel-Prize type of work".
"Given two people of approximately the same ability and one person who works 10 per cent more than the other, the latter will more than twice out-produce the former. The more you know, the more you learn; the more you learn, the more you can do; the more you can do, the more the opportunity."
The logic applies to most aspects of our life.