Cross-Kingdom Genomic Conservation of Human Sleep-Related Gene Orthologs: Phylogenomic Evidence from Chlamydomonas reinhardtii

Sleep is a widespread and evolutionarily conserved process observed in diverse organisms, from jellyfish to mammals, hinting at its origin as a life-supporting mechanism over 500 million years ago. Although its fundamental purpose and mechanisms remain unclear, the evolution and adaptive significance of sleep continue to be debated. This study explores the evolutionary origins of sleep using Chlamydomonas reinhardtii as a model organism, identifying 145 orthologs analogous to known sleep-related genes across species, highlighting the evolutionary conservation of sleep-regulating pathways. Additionally, discovering uncharacterized proteins with high sequence similarity and significant e-values suggests unexplored roles in sleep regulation, underscoring the potential of C. reinhardtii to reveal new insights into the molecular basis of sleep. This work provides a foundation for identifying previously unknown sleep-associated proteins, particularly within single-celled organisms, which may offer novel perspectives on the biological role of sleep. The study demonstrates that phylogenomic analysis of diverse model organisms can expand our understanding of the evolutionary trajectory of sleep and its fundamental function, paving the way for further research in sleep biology and its health implications. Overall, the fundamental functions of sleep observed in higher animal phyla originated from its primordial activities, demonstrating an evolutionary continuum wherein more specialized tasks were integrated with sleeps essential restorative properties.