In March 2017 researchers from Japan published the results of their study to assess the association between depressive symptoms and morningness-eveningness (ie the degree to which people prefer to be active in the morning or the evening), sleep duration and rotating shift work. A total of 1,252 day workers and 1,780 rotating shift workers, aged between 20-59 years, were involved in the study. Information on depressive symptoms, morningness-eveningness and sleep habits were collected via a self-administered questionnaire. Results showed that the level of depressive symptoms was significantly higher in shift workers than day workers and in addition there was also a greater eveningness in shift workers. When sleep duration was assessed, those shift workers on the day shift had a significantly shorter sleep duration than those who only worked during the day. A further analysis revealed that greater eveningness and shorter sleep duration of the rotating shift workers both appeared to be associated with a higher incidence of depressive symptoms. An association between morningness-eveningness and a short sleep duration were also seen to be associated with a higher level of depressive symptoms in those who only worked during the day.
Togo F et al. Association between depressive symptoms and morningness-eveningness, sleep duration and rotating shift work in Japanese nurses. Chronobiol Int. 2017;34(3):349-359