Across the animal kingdom, sleep during early life is essential for brain development and cognitive functions. Like in humans, the fruit fly Drosophila melanogaster also sleeps. Research in Drosophila has generated breakthroughs in the genetics and neurobiology of sleep. However, studies in flies have almost exclusively focused on mechanisms in adulthood. Recently, Matthew Kayser’s laboratory pioneered the discovery that Drosophila larvae sleep, establishing a powerful system for investigating the mechanisms regulating sleep during early development. In terms of mechanisms, much is known about the neural circuits that control sleep, however, recent evidence in a variety of species including Drosophila, has suggested that in adulthood, sleep is modulated by Blood Brain Barrier (BBB), a semi-permeable membrane with a protective role for the central nervous system. Importantly, the BBB is fully established from early development in Drosophila, however its role in larval sleep has not been evaluated, which is the main goal of my research. Together, my findings support the idea that BBB signaling is relevant for larval sleep, possibly utilizing mechanisms distinct from those involved in BBB-sleep interactions in adult flies. Advancing our understanding of sleep during early development in Drosophila and how it is regulated by the BBB may provide valuable insights into developmental sleep mechanisms across species.