In a new working paper , the economists Edward E. Leamer, of UCLA, and J. Rodrigo Fuentes, of Pontificia Universidad Católica de Chile, studied data about working hours from the American Community Survey. They found that hours worked since 1980 increased nearly 10 percent for Americans with bachelor’s and advanced degrees. Leamer told me that he believes this is because computing has shifted much of the economy from manufacturing to neurofacturing, Leamer’s term for intellectually intensive white-collar labor that is often connected to the internet, such as software programming, marketing, advertising, consulting, and publishing.

Neurofacturing jobs lend themselves to long hours for several reasons, Leamer said. They’re less physically arduous, as it’s easier to sit and type than to assemble engine parts. What’s more, the internet makes every hour of the day a potential working hour.

If the operating equipment of the 21st century is a portable device, this means the modern factory is not a place at all. It is the day itself. The computer age has liberated the tools of productivity from the office. Most knowledge workers, whose laptops and smartphones are portable all-purpose media-making machines, can theoretically be as productive at 2 p.m. in the main office as at 2 a.m. in a Tokyo WeWork or at midnight on the couch.

As Leamer and Fuentes write in the paper, “The innovations in personal computing and internet-based communications have allowed individual workers the freedom to choose weekly work hours well in excess of the usual 40.”

The internet has also supercharged global competition and forced international firms to outwork rivals many thousands of miles away. This has created a winner-take-all dynamic that’s trickled down to the workforce. In their 2006 study, “Why High Earners Work Longer Hours,” the economists Peter Kuhn and Fernando Lozano found that the premium paid for longer workweeks has increased since 1980 for educated workers, but not for less educated workers. Their theory is that at the most competitive firms, ambitious workers putting in super-long hours are sending a clear message to the boss: Promote me! And the boss isn’t just getting the message; he’s actively soliciting it. At many firms, insanely long hours are the skeleton key to the C-suite and the partner track. Thus, overwork becomes a kind of arms race among similarly talented workers, exacerbated by the ability to never stop working, even at home. It’s mutually assured exhaustion.