The Mourrain lab's approach to studying sleep is to use simpler organisms amenable to molecular studies such as D. melanogaster, C. elegans and Danio rerio (zebrafish). While unquestionably superb genetic model organisms, the phylogenetic distance between invertebrates and mammals has produced notable and relevant divergences in usage of neuromodulators. While most mammalian peptidergic neurotransmitter systems are not present in flies and worms, we have characterized the hypocretin (HCRT) and the "true" Melanin-Concentrating Hormone (MCH) neuropeptidergic systems in zebrafish. The lab has shown that, despite some differences, these circuits are mostly similar in zebrafish, with conserved functions in sleep and feeding regulation.