Shift and Night Work in Technology Intensive Environment as a Health Hazard

Abstract

Flexible workday arrangement is a common management practice in the modern technology intensive society. The impact of shift work in night hours on human health has been a subject of a broad range of fundamental and applied studies in occupational medicine and in other fields. Epidemiological data and a body of research findings suggest that shift workers are prone to various pathologies. This paper summarizes current views on the link between shift and night work and the risk of chronic noncommunicable diseases (NCDs), which are a leading cause of morbidity and mortality among working population and are therefore a top priority. Systematic reviews and meta-analyses present strong evidence that shift workers have a higher risk of malignant tumors (breast cancer, prostate cancer, colorectal cancer), coronary heart disease, and type 2 diabetes compared to daytime-only workers. There are, however, individual differences in the risk of NCDs that may depend on the length of employment and other circumstances. Also, factors are discussed that can modify the impact of shift work on the risk of associated pathologies, such as chronotype, changing length of night shifts, proper shift rotation, sufficient rest between shifts, etc. Mechanisms of genetic regulation of individual circadian rhythms and sleep-wake cycle are a crucial element in the conceptual model of influence of night work on body. Insufficient adaptation and plasticity of the circadian system may cause desynchronization between external time and inner biorhythms in shift workers; this is accompanied with changes in circadian genes expression and may lead to pathologies. If disturbed circadian rhythms are the main factor of etiopathogenesis, the term “circadian-related disease” should be used. Deep understanding of the link between circadian desynchronosis and health problems in shift workers is important to implement ‘circadian safety’ measures, i.e. to protect workers from negative consequences of disturbed individual biorhythms that may affect their work capacities and life quality. This will require standard protocols to study circadian disturbances, standard tools and methods to diagnose circadian rhythms in workers, resolving issues of interpretation in respect of occupational capacity, research on proneness and tolerance of workers to circadian-related problems, finding pharmacological and physical approaches to reduce circadian disturbances, considering special aspects of drug therapy of desynchronosis.