The daily rhythms in various physiological processes are generated by endogenous circadian clock and the circadian machinery is proposed to contain transcription–translational feedback loops involving period, timeless, clock and cycle genes. In Drosophila, circadian clocks regulate a myriad of behavioral and physiological processes such as sleep, adult emergence, learning, memory and metabolism. Among the clock controlled behaviors, sleep is most mysterious and less understood phenomena exhibited by organisms. My work focuses on the neurotransmitters and neuropeptides involved in the temperature mediated and metabolic signal mediated sleep in Drosophila melanogaster. Studies on sleep genetics and circuitry provide important contributions to our understanding on genetic basis of sleep disorders. Apart from this, I am also probing microRNA mediated post-transcriptional regulation of circadian clock gene expression and its impact on behavioral rhythms. To this end, I use comprehensive genetic, neurobiological and molecular approaches in Drosophila melanogaster.