Shift workers at increased risk of obesity
Individuals involved in shift work have greater odds of becoming overweight or obese, as shown in a systematic review and meta-analysis.
Researchers pooled data from 26 studies (seven cohort studies, 18 cross-sectional studies and one case–control study) involving 311,334 participants. The studies examined the impact of shift work (nonshift schedule vs night shift, rotating shift or mixed schedule) on the prevalence or incidence of overweight or obesity.
There was substantial heterogeneity identified among the studies, as the cutoff points of overweight and obesity varied greatly. Nevertheless, the results were consistent. Shift work increased the risk of overweight by 25 percent (relative risk [RR], 1.25; 95 percent CI, 1.08–1.44) and of obesity by 17 percent (RR, 1.17; 1.12–1.22).
Researchers highlighted circadian disruption, which has been shown to impair glucose metabolism and lipid homeostasis, as a potential biological explanation for the involvement of shift work in the pathogenesis of obesity. Melatonin is an important mediator of circadian disruption resulting in shift work-related obesity. The production of this hormone is promoted in the darkness but suppressed in the presence of light at night, so shift work could inhibit the secretion of melatonin. [Curr Opin Lipidol 2009;20:127-134]
Sleep deprivation is also involved in the pathogenesis of obesity, with evidence showing an association between chronic sleep deprivation and long-term weight gain. Sleep disturbance contributes to overweight and obesity by adversely influencing hormonal rhythms and metabolism. [Proc Natl Acad Sci USA 2013;110:5695-5700; Int J Obes 2008;32:1825-1834]
In light of the increasing prevalence of shift work and the potential adverse effects of overweight/obesity on health, the current findings suggest that both the managers in charge of working time organization and the involved workers must be appropriately informed about the possible negative consequences of shift work, researchers said.
Shift schedules should be designed such that circadian disruption and accumulation of sleep deficiency are minimized in order to limit negative effects on health, they added.