The circadian clock is an endogenous timing system that regulates in a daily manner physiological functions and behavior by modulating gene expression and protein function. Circadian control of transcription regulation is widely studied however the understanding of circadian dynamics in protein function is in its infancy. My work in the last years has pioneered the use of mass-spectrometry (MS) based quantitative proteomics to study temporal dynamics of protein abundance, cellular localization and post-translational modifications (PTMs). This technology has thus proven instrumental in chronobiology to comprehensively understand post-translational mechanism regulating circadian metabolism and physiology. Our group will continue using this state of the art technology to further study basic circadian molecular mechanism as well as metabolic, behavioral and cognitive disorders associated with circadian asynchrony, a condition frequently associated with modern life styles.