How many studies support Circadian Rhythm?

Shift work is the best human model for studying real-world circadian disruption, and the evidence here is unusually consistent: two independent dose-response meta-analyses find shift work increases cardiovascular disease morbidity and mortality, and a more recent meta-analysis of night shift work specifically confirms elevated cardiovascular risk indicators. That's backed by 9 published studies in Vitaebase's database, including 9 meta-analyses, the most recent from 2025 -- a fairly substantial body of research for a single topic.