The present study was designed to describe the socio-demographic, clinical, and polysomnographic features of patients diagnosed with narcolepsy in our sleep center. This retrospective cross-sectional study was conducted on 181 patients diagnosed with narcolepsy based on the results of clinical evaluation, polysomnography (PSG), and multiple sleep latency test (MSLT) between 1993 and 2009. Approximately 70% of the patients had cataplexy, whereas 42% had hallucinations and 55.8% had sleep paralysis. Although sleep efficiency was higher (91.28 ± 5.89%) in patients with narcolepsy, they woke frequently during the night, and their percentages of deep sleep were low (stage 3, 5.12 ± 3.08%, stage 4, 9.60 ± 7.10%). Our study group was divided into two based on age: individuals aged <30 years (n = 152) and >30 years (n = 29). REM latency on PSG was shorter (t = 2.96, p = 0.004) and sleep onset REM (SOREM) on MSLT was higher (t = 2.56, p = 0.011) in the older group than in the younger group. Cataplexy is seen in most patients with narcolepsy. In older patients, REM latency on PSG is shorter and the number of SOREM on MSLT is higher.