Objectives The prevalence of night shift work is increasing in China. Systematic inflammation is supposed as one of the important pathways which mediate night shift work and metabolic-cardiovascular diseases. This study aims to investigate the relationship between night shift work and leucocyte counts 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. White blood cell counts were determined by automated analyser.

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 leucocytes count of night shift workers was significantly higher than that of day workers after adjusting for age and other confounding factors.

Conclusion These preliminary results suggest long-term night shift work may increase the leucocytes, while these will be updated in the conference. [National Natural Science Foundation of China (Project number 81273172 and 81372964), Shelly@cuhk.edu.hk (Lap Ah Tse)]