The details of the critical reviews and recent reports identified on shiftwork and the risks of CVD are summarized in Table 2. An early review highlighted the possibility of adverse effects of shift work on the cardiovascular system [29]. Two later summaries concluded that a 40% increase in CVD reported by Knutsson et al. [30] in shift workers compared to day workers provided a reasonable estimate for the adverse association [31,32]. In contrast to these reports, a more recent systematic review of the relationship between shift work and IHD concluded that the published findings on shift work and IHD were inconclusive and did not support a causal association [7].