Comparing the Health Impacts of Fixed Night and Rotating Shift Work: An Umbrella Review of Meta-Analyses.

Despite abundant research on the health risks of shift work, studies directly comparing fixed night work and rotating-shift work are relatively rare. This study systematically reviewed and synthesised recent meta-analytic findings to assess how fixed night work and rotating-shift work influence health outcomes. An umbrella review of meta-analyses was conducted, including studies published until December 2024 from PubMed, Embase and Web of Science. Meta-analyses examining health risks by shift type were included. Risk estimates and methodological quality (AMSTAR 2) were analysed. Fixed night shifts were linked to higher risks of ischaemic heart disease (pooled RR: 1.44; 95% CI: 1.10-1.89), increased blood pressure and obesity (pooled OR: 1.43; 95% CI: 1.19-1.71), based on adjusted estimates from the included meta-analyses. Rotating shifts were associated with greater risks of overall cancer risk (pooled OR: 1.14; 95% CI: 1.04-1.24) and pre-eclampsia (pooled OR: 1.75; 95% CI: 1.01-3.01). Fixed shifts showed more melatonin disruption and miscarriage risks (pooled OR: 1.23; 95% CI: 1.03-1.47), while rotating shifts were more strongly associated with impaired sleep quality, characterised by reduced sleep efficiency, shorter sleep duration and increased sleep disturbance. Although it is difficult to conclude definitively which type of shift work is more harmful overall, fixed night shifts appear to pose greater cardiometabolic risks-particularly for ischaemic heart disease, increased blood pressure, Type 2 diabetes and obesity-while cancer-related outcomes were more consistently associated with rotating shift work.