Objectives As an indispensable job nature, night shift work may cause the night work disorder, working stress and emotion problems. This study aims to investigate the relationship between night shift work and depression by analysing the baseline data of a prospective night shift workers cohort.

Methods We are establishing a prospective night shift worker cohort in Shenzhen, China. More than 70,000 workers were recruited till the end of 2015. A standardised questionnaire is used to collect information on lifetime night shift work, light at night, occupational hazards, sleep disorders, etc. Diseases history and medicine taking of recent two weeks were also collected by the questionnaire. Depression was assessed by the Patient Health Questionnaire-9 (PHQ-9) depression test questionnaire.

Results Currently, we reported data from 1338 day workers and 398 night shift workers with a response rate of 95%. The shift workers are about two-years younger than day workers. The smoking and alcohol drinking status are comparable in two groups. The prevalent of moderate-severe depression is 1.6% among all participants. However, the prevalence of depression is no deferent between night shift workers and day workers after adjusting for age and other confounding factors.

Conclusion These preliminary results didn’t support that long-term night shift work may increase the risk of depression, while this result will be updated in the conference after fully considering of sleep disorders. [National Natural Science Foundation of China (Project number 81273172 and 81372964), Shelly@cuhk.edu.hk (Lap Ah Tse)]