Abstract Introduction Narcolepsy is a sleep disorder characterized by hypersomnia and inappropriate intrusion of REM sleep into wakefulness. Etiology is heterogeneous, and is broadly classified into Narcolepsy Type 1 and Type 2. There is growing evidence that the pathogenesis in many cases have a post-infectious autoimmune basis. We present the case of a patient seen in our sleep clinic who was eventually diagnosed with Narcolepsy type 2 following West Nile Virus (WNV) Meningoencephalitis. Report of Cases: · The patient is a 44 year old Hispanic woman who had no prior sleep difficulties before 2013, when she was diagnosed with WNV meningitis. Lumbar puncture results from the time of infection are not available, as this evaluation occurred in the Dominican Republic. Subsequent lumbar punctures have shown the presence of anti-WNV IgG antibodies in her CSF. MRI and MRA brain were unremarkable. · She also has a history of migraine, fibromyalgia, depression, and adrenal insufficiency. · She presented with sleep complaints, including sleep onset insomnia, symptoms of sleep disordered breathing, and excessive daytime sleepiness. · She underwent home sleep apnea test in 12/2020 which revealed mild obstructive sleep apnea. Overall AHI was 7.9/hour without significant hypoxemia. She was subsequently started on CPAP therapy with good adherence, but she continued to have significant daytime sleepiness, notably with an Epworth Sleepiness Scale score of 21/24. · She subsequently underwent overnight polysomnogram and multiple sleep latency test in our sleep laboratory. · Overnight PSG confirmed mild obstructive sleep apnea (AHI 12.0) along with short REM latency (10.5 minutes). Next day MSLT showed mean sleep latency of 2.3 minutes, for 5 attended naps, with 2 SOREMPs, which was diagnostic of Narcolepsy type 2. Conclusion This case demonstrates the onset of narcolepsy after WNV meningoencephalitis. Support (If Any)