Shift work, social jet lag and 24/7 lifestyles are thought to add to the burden of metabolic disease facing modern society. Erratic sleep–wake patterns, changing meal times and artificial light exposure lead to dyssynchrony of our internal body clocks, potentially increasing the risk of obesity, hyperglycaemia and dyslipidaemia.

Báez-Ruiz and colleagues, from the group of Ruud Buijs, induced circadian disruption in rats by housing them in constant light, rather than a standard cycle of 12h light–12h darkness. This disrupted their rhythms of activity and of circulating corticosterone, and resulted in triglyceride accumulation, hyperinsulinaemia and impaired glucose tolerance.

Restricting the rats’ feeding periods to 12-h windows ameliorated glucose handling, but did not improve other metabolic parameters affected by constant light. However, restoring hormonal rhythms with timed administration of melatonin and corticosterone (secreted in a piece of apple), in phase with feeding, did restore liver triglyceride, bile acids and glucose handling to levels comparable with those in animals housed in a light–darkness cycle. It remains to be seen whether such strategies might translate to humans working nightshifts.

Read the full article in Journal of Endocrinology 235 167–178