Burnout is persistent physical, mental or emotional exhaustion caused by long-term stress, usually as a result of excessive workplace and/or personal responsibilities.
Because burnout cannot coexist with engagement, it's a serious problem for the enterprise. Burnout is associated with higher stress levels, poorer performance, more illnesses and absenteeism, and less productivity. In a corporate culture that places high demands on employees, the cumulative effect can be lower profitability and higher staff turnover.
The concept of burnout comes from psychology. Herbert Freudenberger, a clinical psychologist, first identified the concept in the 1970s. Social psychologists Christina Maslach and Susan Jackson subsequently developed an assessment tool, the Maslach Burnout Inventory, that characterizes burnout as a syndrome involving exhaustion, cynicism, and inefficacy. The predominant characteristic of burnout is often considered to be exhaustion.
Burnout is not considered a separate disorder because it overlaps significantly with depression. A recent study by Bianchi, Schonfeld, and Laurent found that 90 percent of workers identified as burned out also met diagnostic criteria for depression.
Depending on the particular case, burnout may be alleviated by changes in the work environment and job demands, as well as changes in the individual's behavior and approach to work. If nothing changes, however, burnout tends to create a downward spiral, in which an unsustainable situation leads to exhaustion and dissatisfaction, which lead to poorer performance, which in turn leads to a worsened work situation or even job loss and increased stress on the individual.
See Shawn Achor's TED talk, "Stop working hard. Start working happy."