Narcolepsy is a chronic hypersomnia characterized by excessive daytime sleepiness and manifestations of disrupted rapid eye movement sleep stage. Not all symptoms are present in all patients and these may vary and in frequency and intensity over time. Although the specific causes of narcolepsy remain unknown, it appears that there are both environmental and genetic factors contributing to the development of this disease. Narcolepsy can begin at any age, although the majority of the people diagnosed with narcolepsy begin to show symptoms between the ages of 10 and 25 yr. Younger populations report that excessive daytime sleepiness was the first symptom to appear. Prevalence estimates have been reported to be between 168 and 799 per 100,000 in most studies. A 12-years old schoolgirl (grade 7) was presented to our outpatient clinic with complaints of “daytime sleepiness, inattention and fatigue”. According to history obtained from the patient and her mother, it was found out that her complaints began 3 years ago where she felt asleep at home after school and failed to awake despite all efforts of family who broke the door to enter home. Her mother stated that complaints became more severe since then. The patient stated that she felt sleepiness and tiredness throughout daytime even she slept all night and she was falling asleep while eating, walking and standing. Recently, sleep episodes began to occur 2-3 times per day. She felt asleep following the first one or two lessons in the school. Thus, she has experienced difficulty to follow lessons. There was decreased academic success when compared to previous academic level. The patient’s friends were sending up her because of this condition. Thus, her relationship with friends was disrupted and she had increased timidity. She stated that she was intensively thinking her disease and she was curious when her disease will over and how disease will affect her future. She was assessed by a psychiatrist 2 years ago and modafinil therapy was initiated. Although the therapy was effective at short-term, symptoms were recurred subsequently. One year ago, she received şuoxetine therapy for 3 months with a diagnosis of depression but no beneficial effect was observed. OROS-MPH therapy was initiated by consideration of narcolepsy. There was marked improvement in daytime sleepiness, fatigue, inattention, and depressive symptoms and the patient is still attending follow-up visits. The background level of sleepiness can also have significant impact on daytime functioning, impairing concentration, work and school performance, and general quality of life. Excessive daytime sleepiness is treated with psychostimulants. Emotional and behavioral problems may require antidepressant treatment and supportive psychotherapy. As generally seen in children, hypersomnia episodes were present in our case. Because of sleepiness, the patient had inattention and was incapable to follow her lessons; thus, she had reduced academic success. Her relationship with friends was impaired. In addition, depressive symptoms related to her disease were added. No additional therapy was prescribed as it was considered that attention disorders and depressive symptoms were secondary to narcolepsy.