Workers invented a new category of absence because existing ones would not cover it.
Workplace sick leave policies, formalized in the mid-twentieth century, were designed for physical illness. An employee with a fever or a broken bone had a recognized reason to stay home. An employee who was emotionally exhausted, overwhelmed, or unable to function for psychological reasons did not.1
The phrase "mental health day" entered informal use in the United States during the 1990s to describe a day taken off work for psychological wellbeing rather than physical illness. The term acknowledged what formal policies did not: that a person could be too depleted to work without being sick in any way that a doctor's note could confirm.
The concept gained traction as awareness of workplace stress, burnout, and anxiety increased. The World Health Organization included burnout in its International Classification of Diseases in 2019, defining it as an occupational phenomenon resulting from chronic workplace stress that has not been successfully managed.2
Some employers began formally incorporating mental health days into leave policies in the 2010s and 2020s. Several U.S. states, including Oregon in 2019, passed legislation allowing students to take excused absences for mental health reasons, extending the concept beyond the workplace.3
The mental health day occupies an unusual position. It exists because the system that created sick leave assumed that legitimate absence required a physical ailment. Workers created the concept informally because the formal categories left no room for the reality that work itself could be the thing a person needed to recover from.4