This chapter discusses the case of a 56-year-old man who presented to the sleep clinic complaining of frequent episodes of feeling paralyzed as he was going to sleep. It presents the clinical history, examination, follow-up, treatment, diagnosis, and the results of the procedures performed on the patient. Examination revealed a pleasant, thin, middle-aged man, in no acute distress, who looked younger than his stated age. Based on the history, the diagnosis of isolated or familial sleep paralysis was made and the patient was started on clomipramine 25 mg at bedtime. Differential diagnosis includes narcolepsy if excessive daytime sleepiness (EDS) is present or a history of hypnic hallucinations and cataplexy can be elicited. Although daytime sleepiness is necessary to make the diagnosis of narcolepsy, sleep paralysis can also occur in other conditions that present with daytime sleepiness such as sleep deprivation, sleep-related breathing disorder and idiopathic hypersomnia.