Oxford University researcher Dr. Paul Kelley found that forcing people to start work before 10am causes measurable physiological stress, disrupting the body’s natural circadian rhythm and elevating cortisol levels significantly. He presented the findings to the British Science Association and called early start times a form of systematic social jet lag.
He argued that starting work at 10am would improve productivity, mental health, and physical wellbeing across the board. The nine-to-five schedule was designed around factory shifts, not human biology.