Signal Four-Day Work Week + AI Productivity Convergence — Nature Human Behaviour RCT

Summary

The Nature Human Behaviour study, published in July 2025, was led by Boston College sociologists Wen Fan and Juliet Schor and is described as the largest controlled trial of the four-day work week to date, covering 2,896 employees across 141 organizations in the US, UK, Canada, Ireland, Australia and New Zealand. Companies were given roughly eight weeks to restructure workflows before adopting a four-day week, and outcomes were compared against a control group of 562 employees at 12 companies that kept the traditional five-day schedule. For most participating companies, employees shifted from a 40-hour to a 30-hour week, yet 90% of companies chose to retain the four-day schedule after the trial, with workers reporting less burnout and improved mental and physical health while self-assessing that they were just as productive. Researcher Wen Fan noted a counterintuitive finding: workers did not simply work faster to compensate and sacrifice well-being to maintain output, contrary to what researchers initially expected. The result converges with separate discussions of AI productivity gains on the broader question of how working hours should be set.