Dietary restriction, circadian fitness, and ageing: insights from Drosophila

Circadian clocks orchestrate the daily timing of numerous physiological processes, and their synchronization is essential for organismal health. Growing evidence links disruptions in circadian timing to ageing. Separately, dietary restriction is a robust intervention for extending lifespan and healthspan, and emerging studies suggest the circadian system may mediate these effects. Yet how dietary restriction, ageing, and the brain's circadian clock interact remains unclear. We argue that Drosophila melanogaster is an ideal model to dissect this relationship, given its short life cycle, well-characterized clock machinery, and extensive genetic tools. We tracked locomotor activity in individual flies across their lifespan, exposing them to diets varying in yeast content, the main protein source in laboratory food. Lowering yeast intake extended lifespan and enhanced circadian and sleep fitness in young and early-aged flies, but not in flies older than 5 weeks. These results support the value of Drosophila as a platform for investigating the crosstalk between circadian health and ageing.