Freelancers in the crowd may have noticed a puzzling phenomenon in their lives over the years: that within a day or two of completing a major project they become sick with a cold or other illness. This has happened to me more times than I could shake a stick at (if, that is, I was the stick-shaking type). I always assumed that my body was gamely fighting off infection while the deadline loomed, and then let things go once the project was safely in the can. Now I'm wondering if I was succumbing to leisure sickness.

This phrase was coined by Dutch psychologists Ad Vingerhoets and Maaike van Huijgevoort, who presented a paper titled Leisure sickness: An explorative study at a meeting of the American Psychosomatic Society on March 7, 2001. Symptoms include headaches (even migraines), fatigue, muscular aches and pains, and illnesses such as colds and flus. Sufferers (and for about 3% of the population, this occurs every weekend), typically have, according to the authors, an "inability to transition from the work to the non-work environment, a high need for achievement and a high sense of responsibility." Or they may simply have a work-friendly immune system.