A 72-year-old woman was referred for a 15-year history of brief attacks of generalized weakness that occurred when she was tense or startled. During these episodes, she squatted, closed her eyes, and had difficulty speaking, but there was no disturbance of consciousness. The cerebrospinal fluid level of orexin/hypocretin was low (92 ng/L), leading to a diagnosis of narcolepsy with cataplexy according to the International Classification of Sleep Disorders (ICSD)-2 criteria. Cataplexy should be considered for sudden attacks of weakness lasting less than 2 minutes and with no alteration of consciousness. Measurement of cerebrospinal fluid levels of orexin/hypocretin is recommended when the diagnosis is uncertain.