Salt,　commonly　known　as　sodium　chloride,　is　an　important　ingredient　that　the　body　requires　in　relatively　minute　quantities.　However,　consuming　too　much　salt　can　lead　to　high　blood　pressure,　heart　disease　and　even　disruption　of　circadian　rhythms.　The　biological　process　of　the　circadian　rhythm　was　first　studied　in　Drosophila　melanogaster　and　is　well　understood.　Their　locomotor　activity　gradually　increases　before　the　light　is　switched　on　and　off,　a　phenomenon　called　anticipation.　In　a　previous　study,　we　showed　that　a　high-salt　diet　(HSD)　impairs　morning　anticipation　behavior　in　Drosophila.　Here,　we　found　that　HSD　did　not　significantly　disrupt　clock　gene　oscillation　in　the　heads　of　flies,　nor　did　it　disrupt　PERIOD　protein　oscillation　in　clock　neurons　or　peripheral　tissues.　Remarkably,　we　found　that　HSD　impairs　neuronal　plasticity　in　the　axonal　projections　of　circadian　pacemaker　neurons.　Interestingly,　we　showed　that　increased　excitability　in　PDF　neurons　mimics　HSD,　which　causes　morning　anticipation　impairment.　Moreover,　we　found　that　HSD　significantly　disrupts　neurotransmitter-related　biological　processes　in　the　brain.　Taken　together,　our　data　show　that　an　HSD　affects　the　multiple　functions　of　neurons　and　impairs　physiological　behaviors.