We will investigate the role of the circadian clock in energy balance, metabolism and lifespan of C. elegans.The evolution of life on Earth has been dominated by the influence of the daily rhythms imposed by its rotational movement. As a consequence, endogenous circadian clocks are present in organisms from all phyla, helping them to anticipate the daily cycles in their environment. This endogenous clock gets information from external cues (zeitgebers) in order to synchronise internal timing to the 24 h day. Circadian clocks regulate processes from gene expression to behaviour, resulting in rhythms in metabolite levels and food intake. The disruption of circadian rhythms has been linked to many pathological conditions, including sleep disorders, depression, metabolic syndrome and cancer. As obesity becomes epidemic in industrialized societies in parallel with a well-documented disruption of our circadian rhythms, the relationship between them becomes highly relevant. We propose to investigate this problem using the nematode C. elegans, an emergent model for the study of circadian rhythms and already established for metabolic research.