People who lack stimulation in their working lives are likely to be depressed and suffer from headaches, fatigue and recurrent infections, all symptoms of "underload syndrome".
—Hermione Eyre, "A nerve-racking, stressful, exhausting life? Yes, please!," The Independent, May 4, 2003

"Boredom has exactly the same effect on the body as stress," says Dr Martyn Dyer-Smith, a psychologist at the University of Northumbria. "People who are normally busy can become ill when they don't have enough to do, because it sends their levels of stress hormones shooting up." ...

And it's not just our leisure time that is putting our health at risk. A lack of stimulation at work can have similar negative effects — known to psychologists as "underload syndrome". Studies at the University of Northumbria found that bored people have more days off sick than any other group. ...

The most common health complaints triggered by underload syndrome are headaches, fatigue and recurrent infections; it is also a cause of mild depression. Research shows that highly strung people and those who are always on the go are most at risk. High-flyers are particularly vulnerable, according to Dyer-Smith, because they have perfected their skills and therefore are able to perform their jobs with little effort.
—Lucy Elkins, "Bored sick," Sunday Times of London, February 2, 2003