Circadian ClocksCLOCK ProteinsCircadian RhythmBiological ClocksARNTL Transcription FactorsPeriod Circadian ProteinsCryptochromesPhotoperiodCircadian Rhythm Signaling Peptides and ProteinsNuclear Receptor Subfamily 1, Group D, Member 1LightFlavoproteinsDarknessBasic Helix-Loop-Helix Transcription FactorsChronobiology DisordersFeedback, PhysiologicalPhotoreceptor Cells, InvertebrateTranscription FactorsGene Expression RegulationE-Box ElementsDrosophila ProteinsActivity CyclesNuclear Proteins