A protein linked to ageing and metabolic disease might control the brain's internal clock.

The protein SIRT1 regulates the expression of many genes and has been linked to daily biological cycles called circadian rhythms in tissues such as fat and the liver. Hung-Chun Chang and Leonard Guarente at the Massachusetts Institute of Technology in Cambridge found that in mouse brains, SIRT1 switches on two proteins that are known to regulate circadian rhythms.

Aged mice were slower than young mice to adjust to shifts in light–dark cycles, and expressed lower levels of SIRT1 in the brain region that sets circadian rhythms. Boosting SIRT1 levels shortened animals' adjustment time, whereas depleting SIRT1 lengthened it.

Cell 153, 1448–1460 (2013)