Last week, an emotional Elon Musk described how he was working so hard to keep production of the Tesla Model 3 on track that he missed his own birthday. “All night – no friends, nothing,” he told the New York Times, apparently “struggling to get the words out”. Musk had, he said, been working 120-hour weeks, often not leaving the factory for three or four days. When he did get home, he said, the choice was between no sleep or taking an Ambien, an insomnia drug intended for short-term use (and blamed by some of Tesla’s board members for his erratic night-time tweeting).

Musk has long been celebrated by the business press for his work ethic. His extraordinary schedule – a long working day broken into five-minute increments, so that every second is accounted for (lunch is usually wolfed down in a meeting) – has been reported, approvingly, for some years now. And certainly, Musk has more on his plate than many chief executives. As well as running Tesla, the first mass-market car company to be founded in the US in decades, he is the head of SpaceX, which aims to fly people to Mars, and Neuralink, a company attempting to build a brain-computer interface.

The only reason he is not even more busy is because he resigned from the board of OpenAI, a non-profit founded to create “safe artificial general intelligence”, when he decided there was a conflict of interest with Tesla’s own AI projects; and because he is no longer the chairman of his cousins’ solar panel company, Solar City, since Tesla bought it wholesale in 2016.

He also has five children.

Historically, the boss who dedicates his life – every second of it – to corporate success has been an icon of the US boardroom, nowhere more so than in Silicon Valley. Tech bosses have typically combined the pressure of being an executive managing millions with the optimise-everything mentality of a typical engineer, while the straight-out-of-college age of many first-time entrepreneurs is a perfect storm for a level of dedication to workplace productivity that verges on the dangerous. Not just dinners at the office and a sleeping bag under the desk, but 5am starts after an hour at the gym, breakfast replaced by “bulletproof coffee” (coffee with butter in it, but apparently healthy) and interspersed with spells of “intermittent fasting”. Then there is the tendency to take client calls while in the check-in queue for your third international flight in as many days.

Could Musk’s tearful disclosure be the moment all that changes?

Arianna Huffington, another multimillionaire with her fingers in multiple pies, led the reaction to his interview, with an open letter on her Thrive Global website imploring Musk to “give yourself time to reconnect not just with those you love but also with yourself and your wisdom”.

Facebook Twitter Pinterest Sky-high dreams: Musk unveils the Dragon V2 space taxi in 2014. Photograph: Bloomberg via Getty Images

“This is not about working hard,” Huffington wrote. “It’s about working in a way that allows you to make your best decisions. Working 120-hour weeks doesn’t leverage your unique qualities, it wastes them. You can’t simply power through – that’s just not how our bodies and our brains work. Nobody knows better than you that we can’t get to Mars by ignoring the laws of physics. Nor can we get where we want to go by ignoring scientific laws in our daily lives.”

Musk was having none of it. In a tweet sent at 2:30am, he told her “Ford & Tesla are the only 2 American car companies to avoid bankruptcy. I just got home from the factory. You think this is an option. It is not.”

On Monday, Huffington responded, telling CNN that “This is not about sleep, or about slowing down, or about asking Elon to chill out under a mango tree … It’s about how we can unlock and sustain our peak performance, and see solutions and opportunities where others can’t.”

Everything we know about a healthy working life supports Huffington, says André Spicer, professor of organisational behaviour at the Cass Business School in London. “There’s lots of evidence that having no boundaries between work and life, and allowing work to infest your whole life, can be very damaging for productivity.”

Forthcoming research from Spicer’s colleague Hans Frankort, for example, shows that greater work effort – measured in both time and intensity – not only leads to reduced wellbeing (as even Musk may agree), but also worse career outcomes. In fact, intensity, measured by whether people described their job as requiring working at “very high speed” or to “tight deadlines”, was an even stronger predictor of bad outcomes than whether or not employees had to work overtime.

Frankort and his co-author Argyro Avgoustaki call for “genuine consideration” of initiatives to reduce exposure to intensive work, but acknowledge that it will “take time to unfold and may encounter resistance”.

Silicon Valley has long been one of the leading exporters of the unending work day. The technology sector is, of course, responsible for the tools that people have used, firstly to bring work home, then on holiday and, eventually, everywhere: the networks, laptops and smartphones that mean that leaving the workplace no longer means leaving work.

It has also been pioneering an approach to workplace design that encourages a round-the-clock schedule. With free breakfasts, lunches and dinners, on-campus gyms and running tracks and rec rooms filled with games and toys, it is easy to see why some tech workers spend every waking hour somewhere in the office.

And, increasingly, their sleeping hours, too. Google and Facebook have both proposed building “self-contained towns” near their main campuses in the Bay Area, slotting hundreds of apartments into the companies’ already sprawling complexes. It is not a huge stretch, really, when you consider the employees who are already taking their home to work, including the Google employee, Brandon, who was revealed, in 2015, to be living in a van in the office’s car park.

Facebook Twitter Pinterest Tesla’s building in Fremont, California. Photograph: Bloomberg via Getty Images

Other typical Silicon Valley perks take on a similarly dark tinge when they are considered more closely. Policies that allow employees to take unlimited holidays, for instance, sound great. But, according to Sage Business Review, “instead of taking too many days, most committed employees don’t take enough”. The problem is so bad that some places that offer unlimited holidays have had to introduce a second minimum-vacation policy to prevent employee burnout, as staff, unsure of how much time off was the “right” amount, opted to just take none at all. (The prospect of unlimited holidays is one of the more divisive offers among British workers, with broadly equal numbers of supporters on each side, according to the intelligence platform Streetbees.)

And where Silicon Valley leads, others follow, says Spicer. “This kind of hyper-work ethic is very common, not just in Silicon Valley, not just in investment banks, but in many, many organisations,” he says. “And the reason is that companies tend to copy each other. Many companies look toward iconic Silicon Valley firms as the example of what they should be like. So they look at what Elon Musk is doing, or whoever, and no matter what kind of organisation they have, they often copy what these other firms are doing, just because if they are successful, they think, well, what’s their secret sauce? Whatever they can see visibly, they copy that.” The problems caused by this culture are widespread. According to Streetbees, which investigated the question for the Guardian, four in five people in the UK say they feel guilty calling in sick when unwell, and 64% say they find it hard to disconnect from work after leaving for the day. It’s not surprising, then, that 77% agree that we don’t have a good work/life balance in the UK.

The recent, highly accelerated commitment to work and efficiency can reach levels that even some Silicon Valley types see is A Bit Much. In 2013, for instance, the meal-replacement kit Soylent was launched by software engineer Rob Rhinehart, after he “began to resent the fact that he had to eat food at all”. Rhinehart – with no previous nutritional experience – mixed together a bunch of off-the-shelf nutrients ordered online, and created a 400-calorie slurry that, he hoped, would provide everything he needed to live.

Five years on, Soylent no longer advertises itself as a complete replacement for food (“Keep in mind that, while Soylent can replace any meal, it is not intended to replace every meal,” the company tells customers), but it has been popular enough to raise almost $75m (£58m) in funding from venture capitalists and attract competitors in the market such as UK-based Huel).

Rhinehart’s dedication to efficiency in other areas of his life hasn’t achieved quite as much take-up, however. In 2015, he wrote about how he gave up a mains connection, instead trying to live entirely from solar cells. A noble goal, achieved through some unconventional methods: “I enjoy doing laundry about as much as doing dishes,” he wrote. “I get my clothing custom-made in China for prices you would not believe and have new ones regularly shipped to me. Shipping is a problem. I wish container ships had nuclear engines but it’s still much more efficient and convenient than retail. Thanks to synthetic fabrics, it takes less water to make my clothes than it would to wash them, and I donate my used garments.”

But while they still have their fans, Rhinehart and Musk’s unflinching dedication to work is increasingly viewed as an unhealthy reflection of a past Silicon Valley would rather forget. As a generation of dotcom founders have grown up, and looked back at their careers, they have realised that maybe they didn’t quite get the balance right – and are determined that the next generation doesn’t repeat their mistakes.

“When my children were young, I thought what I was doing at work was far more important and urgent than what was going on at home,” Scott Weiss, a serial entrepreneur and early partner at influential venture capital firm Andreessen Horowitz, wrote in 2015. Later, he said: “I realised that committing to my family required disconnecting from work (eg turning off the computer and phone), and focusing all of my attention on the details of the home. Cooking a great meal. Helping with a science project. Discussing the future with my partner.

“I’ve observed that CEOs in their 20s may be fully equipped and knowledgeable enough to handle leading a company, but when their family life begins to expand and demand for their attention increases, they are at a loss as to why things aren’t just falling into place … Still, I’m hopeful.”

Driving down Sand Hill Road, the centre of Silicon Valley’s venture capital industry, last weekend, a friend who moved to the area recently remarked on the emptiness of the parking lots. “I thought they were supposed to be at work 24/7,” he said, “but the cars are all gone by 5pm, and at the weekends.”

Facebook Twitter Pinterest Musk is fighting to keep alive the dream of the Tesla Model 3. Photograph: David Zalubowski/AP

Spicer agrees that change is afoot. “If you look at the TED talk universe, and what you find in the Harvard Business Review – the kind of things that managers read – there’s a lot of talk now about how to get sleep, how to protect work/life balance, how to make sure that you have some boundaries around work, how to be mindful,” he says. “And all these things are about saying there’s a boundary between work and life. Work shouldn’t be everything for you, and sleeping in the factory isn’t the best thing to do.”

But while you can take the engineer out of the workplace, you can’t stop them being an engineer, and there is a risk that work/life balance becomes just another thing to optimise for peak performance.

“If you look in the Silicon Valley culture – and this also extends to many corporations,” says Spicer, “executives there are not just obsessed with making their work more productive, but with making their whole life more productive. So they spend a huge amount of time thinking and talking and engaging with these questions about how do you eat in the most efficient way, how do you exercise in the most efficient way, how do you take all these little parts of your life and make them more efficient?”

Nonetheless, even that would be an improvement on the status quo. Spicer argues for a few key changes that would help society, and companies, restore a healthy balance (and, yes, improve productivity). One way would be to ensure enforced time off by mandating holidays and banning out-of-hours email use. Another would be the separation of the core intensive, creative work that many office workers struggle to find time for from the more rote administrative tasks that balloon to fill the rest of the working day.

For Musk, all the advice being proffered his way may still be too late. As he struggles to bring Tesla’s finances into shape – and fulfil a claim that he had “secured funding” to take the company private at $420 a share – he told the New York Times that, “from a personal pain standpoint, the worst is yet to come”.

• This article was amended on 23 August 2018. The original said Elon Musk has six children. His first son died at the age of 10 weeks. This has been changed.

