statement: Sleep deprivation specifically impairs visual selective attention in fruit flies, without affecting behavioural responses to simple visual stimuli. Abstract 1Although sleep-deprivation is known to impair attention in humans and other mammals, the 2 underlying reasons are not well understood, and whether similar effects are present in non-3 mammalian species is not known. We therefore sought to investigate whether sleep is 4 important for optimising attention in an invertebrate species, the genetic model Drosophila 5 melanogaster. We developed a high-throughput paradigm to measure visual attention in 6 freely-walking Drosophila, using competing foreground/background visual stimuli. We 7 found that whereas sleep-deprived flies could respond normally to either stimulus alone, 8 they were more distracted by background cues in a visual competition task. Other stressful 9 manipulations such as starvation, heat exposure, and mechanical stress had no effects on 10 visual attention in this paradigm. In contrast to sleep-deprivation, providing additional sleep 11 using the 5,6,pyridine-3-ol (THIP) did not 12 affect attention in wild-type flies, but significantly improved attention in the learning 13 mutant dunce. Our results reveal a key function of sleep in optimising attention processes 14

Although sleep deprivation is known to impair attention in humans and other mammals, the underlying reasons are not well understood, and whether similar effects are present in non-mammalian species is not known. We therefore sought to investigate whether sleep is important for optimizing attention in an invertebrate species, the genetic model Drosophila melanogaster. We developed a highthroughput paradigm to measure visual attention in freely walking Drosophila, using competing foreground/background visual stimuli. We found that whereas sleep-deprived flies could respond normally to either stimulus alone, they were more distracted by background cues in a visual competition task. Other stressful manipulations such as starvation, heat exposure and mechanical stress had no effects on visual attention in this paradigm. In contrast to sleep deprivation, providing additional sleep using the GABA-A agonist 4,5,6,7tetrahydroisoxazolo-[5,4-c]pyridine-3-ol (THIP) did not affect attention in wild-type flies, but specifically improved attention in the learning mutant dunce. Our results reveal a key function of sleep in optimizing attention processes in Drosophila, and establish a behavioral paradigm that can be used to explore the molecular mechanisms involved.