Sleep has an important role in memory consolidation. In Drosophila and human, sleep deprivation after training leads to memory loss. In contrast to memory deprivation, induction of sleep after training leads to establishment of long-term memory (LTM). Thus, it is conceivable that Drosophila sleep is required for converting initial short-lasting memory into long-lasting form. However, the genetic basis of sleep-dependent memory consolidation is largely unknown. One of the Drosophila LIM homeodomain transcriptional factors, Apterous (Ap), is required for LTM formation because ap mutants show defective LTM using a courtship-conditioning assay, where previous experiences with mated females cause males to subsequently reduce their courtship of virgin females. In addition, our previous study revealed that ap mutant flies show sleep reduction in comparison with wild-type flies and pan-neural knockdown of ap expression by RNA interference (RNAi) also reduces sleep (Neuro2013). Taken these results together, it is possible that the defective LTM in ap mutants results from the dysfunction of memory consolidation induced by reduction of sleep. In this current study, we identified ap-expressing neurons involved in sleep regulation. A neuropeptide, Pigment-dispersing factor (PDF)-producing neurons can be divided into two types [large ventral lateral neurons (l-LNvs) and small ventral lateral neurons (s-LNvs), respectively] and PDF acts on the lLNvs to control arousal/sleep. First, we identified that ap is expressed in some PDF-positive lLNvs and sLNvs using ap::GFP flies with a GFP fusion knock-in allele of ap. Interestingly, targeted expression of ap RNAi in all PDF-producing neurons induced sleep reduction and LTM defect. In addition, lLNv-specific knockdown of ap expression also reduced sleep, indicating that ap expression in lLNvs is required for normal sleep in Drosophila. Thus, ap mutations may cause a decrease of PDF production or release which leads to sleep reduction and results in the dysfunction of memory consolidation.