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Member Research & Reports

Member Research & Reports

Taiwan Researchers Find Insomnia May Underlie the Association between Night Shift Work and Poor Mental Health

Shift workers suffered from more mental health problems, but the risk diminished after adjusting for insomnia, according to a new study by researchers at National Taiwan University College of Public Health. This study was published in the November issue of Occupational and Environmental Medicine. The authors, Dr. Wan-Ju Cheng and Dr. Yawen Cheng, utilized national survey data of 2013 and analyzed the association between shift work and mental health in 19,654 employees.


[Photo: Dr. Wan-Ju Cheng (left) and Prof. Yawen Cheng (right)]

“Mental health and sleep quality in shift workers require more attention,” said Dr. Wan-Ju Cheng, the first author of this study, who is a doctoral graduate from Taiwan and a practicing psychiatrist at the China Medical University Hospital. The demand for shift work is increasing globally and in Taiwan. A recent study indicated that from 2001 to 2010, Taiwanese employees who worked on shift schedules increased from 17 percent to 24 percent. Few protective workplace policies have been implemented to improve shift workers’ health, despite of the abundant evidences which have emerged, showing the impacts of shift work on biological rhythm disturbance, metabolic diseases, cardiovascular risks and mental health problems.

The authors examined psychosocial work conditions, mental health, and sleep problems in workers with different shift schedules, namely fixed day shifts, fixed night shifts, rotating day shifts, and rotating night shifts. Results showed that workers with fixed nightshifts had the shortest duration of sleep, highest level of burnout score, and highest prevalence of insomnia and minor mental disorders. Fixed night shifts were associated with greater risks for short sleep duration and insomnia. However, with adjustment for insomnia, fixed night shifts were no longer associated with minor mental disorders, indicating an intermediating role of insomnia. Furthermore, this study also found that in female workers, rotating day shifts were associated with a greater risk for burnout, which implied a greater double burden from family and work in female shift workers.

These findings send messages to both policy makers and researchers. The senior author of this study, Dr. Yawen Cheng, suggests that some policy initiatives could be adopted by the labor authority. First, shift schedules should be designed to guarantee adequate sleep for shift workers, and both physical and mental health conditions should be more regularly monitored. For workers with mental problems, their labor rights for more suitable work arrangements should be guaranteed and health services should be readily accessible. Secondly, future researches on individual vulnerability to circadian rhythm disturbances by shift work are needed. Practical tools for assessing circadian rhythm, suitability for shift work, and the ability to return to shift wok should be also developed to enhance empirical evidences in research concerning shift work and health.

The leading author of this study, Dr. Wan-Ju Cheng (left), presented a poster in an international conference with her thesis advisor Dr. Yawen Cheng (right).