In a recent appearance on The Joe Rogan Experience podcast, Elon Musk said he sleeps about six hours every night--by necessity, or else his work suffers. That admission by the data-driven Musk is one every overworked startup founder or business manager should take to heart. It applies not only to sleep but to how much you should work and rest in general.

Musk, who recently became the world's richest person and is remaking the auto industry while building tunnels under traffic-clogged cities and preparing to colonize Mars, spent more than two and a half hours talking with Rogan about everything from Neuralink to orbital space flight, to how he originally designed the Model S simply as a car he himself would like to drive.

About five minutes in, Rogan remarks on the many different projects Musk is leading. "How do you have time?" Rogan asks. He adds that he's never understood Musk's ability to build space-going rockets as only one of several businesses. "Well, I do work a lot," Musk answers. "Normally I'd be working until 1 or 2 in the morning." He doesn't usually do that on weekends, he adds, but sometimes he does. 

"How much do you sleep?" Rogan asks. 

"About six hours," Musk answers.

"For someone who does as much as you, that's impressive that you can squeeze that in," says Rogan. (He's known for getting eight hours a night himself). 

"I tried sleeping less, but then total productivity decreases," Musk explains. 

That's one way of putting it. In 2018, Musk famously went off the rails while trying to get Tesla Model 3 production up to speed. First he tweeted that he had "funding secured" for taking Tesla private when that wasn't quite true. The Securities and Exchange Commission sued, and Musk and Tesla each paid a $20 million fine. Musk also had to step down as chair of Tesla's board for two years, although he remained CEO. This was just after he'd earned widespread derision for calling a man involved in rescuing boys trapped in a cave in Thailand "pedo guy" during a Twitter spat over a rescue submarine Musk designed.

Working 120-hour weeks.

With his reputation in a downward spiral, Musk gave a confessional interview to The New York Times, in which he admitted that he was working 120 hours a week, went for days at a time without ever leaving the Tesla factory, and was depending on Ambien the rare times he did sleep. The combination of overwork, exhaustion, and Ambien was at least partly to blame for his self-destructive tweeting. Later that year, he reported cutting back his workload to a "sustainable" 80 to 90 hours a week.

Musk's admission that sleeping less than six hours a night made things worse instead of better is worth taking seriously. Even if your only priority is work (although it shouldn't be), that's still a good argument for getting as much sleep as your body and brain need. Musk seems to have conducted this experiment on himself, and found that sleep is necessary to his own productivity.

In the context of Musk's absurd work schedule and his habit of driving himself beyond human limits, getting six hours of sleep a night is both a healthy step and an admission that working past a certain point is counterproductive, even if you are a genius. And, he tells Rogan, six hours seems to be the right amount for him. "I don't find myself wanting more sleep," he says.

That doesn't necessarily mean he's sleeping enough, according to some sleep experts. They argue that most adults need between seven and nine hours a night and that we should aim to spend more than eight hours in bed, since some of our time there is spent either falling asleep or waking up. And, they say, people can feel perfectly fine but still be sleep-deprived

Reality is that you need adequate sleep every night to be your most creative and most efficient, and also that you'll do your best work if you limit your work hours to a reasonable number and take frequent breaks. People who give themselves plenty of time away from work report getting more done--not less--than if they'd worked longer hours.

Think of it this way: Even Musk, who is famously hardworking and driven, understands the importance of getting good night's sleep and taking time away from work. If he does, so should you.