Circadian rhythmicity and metabolism: integration of metabolic and environmental signals

Circadian rhythms are generated by an internal molecular clock which synchronizes daily physiological variations to the day/night alternance. Many behavioral and physiological processes display circadian rhythmicity, including locomotor activity, sleep/wake cycles and metabolic and endocrine pathways. In peripheral tissues, the molecular clock senses the energy status, is entrained by meal time and responds to metabolites acting as fuel gauges so that the clockwork can gate metabolic fluxes to the most appropriate timeframe. As a consequence, misalignment of the biological clock and environmental signals, as during jetlag or shift work, may result in disruption of metabolic homeostasis. Indeed, mounting evidence from human and animal studies illustrates the relationship between circadian misalignment and cardio-metabolic diseases.