300 volunteers were chosen for the study from among firefighters, train operators, teachers, librarians, and police officers. Nine "stressors" were analyzed, such as size of workload, independence measures, earnings and the like.
Surprisingly, librarians did not fare well in this study. Primary causes, according to the article, concern the lack of control librarians feel they have over their daily work lives, pay levels and the environment of the library. Librarians tended to be absent from work more often than workers in some of the other fields.
Reference: BBC News.