The association between shift work and health: a review

We examined previously published systematic review studies on associations between shift work and health, using the PubMed (MEDLINE) database for our literature search. We eventually selected 30 studies: 2 studies on sleep disorders, 7 on cancer, 7 on metabolic endocrine disorders, 7 on reproduction, 4 on cardiovascular disease, 1 on gastrointestinal disorders, and 2 on the types of shift work and health-related outcomes. Meta-analyses based on quantitative combination of the data from these studies showed that shift work significantly increased the risk of the following disorders: breast cancer, diabetes mellitus, preterm delivery, abortion, low birth weight, small-for-gestational-age infants, menstrual disruption, infertility, ischemic heart disease, and ischemic stroke. Some previous studies had also reported significantly increased risks of sleep disturbance, prostate cancer, body weight change, metabolic syndrome, and fertility and gastrointestinal disorders. Some studies had gathered substantial data, including those obtained from meta-analyses, which indicated significant associations. In contrast, other studies were unable to present sufficient evidence because of the smaller number of data sets included. Therefore, based on these findings, further accumulation of epidemiological studies on this theme is warranted.