A study of government and transit workers in Japan, reported in Sleep (June 2005), confirmed what many individuals know from personal experience: stress at work can negatively impact sleep. Analyzing questionnaire results and health information from men and women employed in both white-and blue-collar jobs, insomnia was determined to be significantly associated with high occupational stress.
Job satisfaction also appears to be an important factor in whether employees develop sleep problems. In the study, both men and women whose jobs required high effort but offered low rewards were especially prone to suffer from insomnia. By contrast, high job stress was associated with "short sleep," defined as <6 hours per night, in men but not in women.
The study authors suggested that the elevated cortisol and hypothalamic-pituitaryadrenal gland axis activation associated with sleep disturbances may be induced by occupational stress. They said that more research is required to determine the definitive causes behind job stress and poor sleep.