Hypnic headache is a rare primary headache disorder diagnosed in approximately 0.1% of all patients with headaches assessed at tertiary headache clinics. It is characterized by recurrent headaches occurring exclusively during sleep and almost always at the same time. Women are affected more than men, and the onset is usually after 50 years of age. Controlled trials have not yet been conducted for the treatment of hypnic headaches because of the rarity of the disorder. Therefore, treatment recommendations are based primarily on case reports and small case studies. Administration of lithium salt has been reported to be effective in the prevention of hypnic headaches; however, it is often intolerable, particularly in the elderly. Several other drugs, such as caffeine, indomethacin, verapamil, flunarizine, gabapentin, and topiramate, have also been reported as being effective.Here, we report a case fulfilling the diagnostic criteria for hypnic headache, as defined in the third edition of the International Classification of Headache Disorders (ICHD-3) beta version. 1 Our patient showed a rapid and excellent response to ramelteon, a selective melatonin MT1/MT2 receptor agonist. 2 An 81-year-old woman visited our outpatient clinic with a 5-year history of headache attacks that woke her up at night. The attacks occurred at least twice a week and always at 2 a.m., approximately 3 hours after falling asleep. The headaches were pulsatile, located in the left temporo-occipital region, and of moderate-to-severe intensity. The patient did not notice any accompanying autonomic symptoms such as lacrimation or rhinorrhea and no symptoms of photophobia, phonophobia, or restlessness. Although some attacks were associated with nausea, there was no vomiting.The headaches lasted for less than 1 hour and resolved spontaneously. The patient reported falling asleep after the cessation of the headache and only 1 attack occurred per night. Indomethacin or loxoprofen did not ameliorate the headaches. There were no instances of headaches during the day. The patient's medical history was unremarkable, apart from mild arterial hypertension, for which she was taking 2.5 mg amlodipine besylate. She was of medium build. Neurological examination, brain magnetic resonance imaging, brain magnetic resonance angiography, and routine blood tests were all unre-