The hypnic headache syndrome is a rare, benign, nocturnal, non-familial headache disorder that occurs only while asleep. Since the first description by Raskin (1) in 1998, the syndrome has been characterized by a diffuse headache that awakens patients at a consistent time of the night, sometimes during a dream, and lasts for 30-180 min. This disorder mainly affects elderly subjects and both sexes equally (2).The pathophysiological mechanism of hypnic headache is not known, but its circadian periodicity and responsiveness to lithium carbonate suggest that perturbation of chronobiological rhythms causes this headache (1). We describe a patient with hypnic headache, which had developed after pontine infarction. To our knowledge, this is the first report of symptomatic hypnic headache that developed after stroke and that suggests direct evidence of a potential pathophysiological mechanism and relationship of hypnic headache to the sleep cycle. Case reportA 71-year-old man visited our headache clinic with complaint of noctural headache. He had a history of hypertension and diabetes mellitus. Two years previously he developed right hemiparesis, dysartheria following vertigo and dysequilibrium of sudden onset. Antiplatelet agents were given to him after the event. Two weeks later, the headache that awakened him from sleep developed. He described the headache as bilateral, dull pressure-like and moderately severe. He was awakened at a consistent time, usually between 02.00 h and 03.00 h, due to headache. The attacks began 2-3 h after he fell asleep and resolved within 1-2 h. He could not tell relationship with dreams exactly. He denied vomiting, nausea, photophobia, phonophobia, or any autonomic symptoms such as lacrimation, nasal congestion, rhi-norrhoea or redness of eye. During the attack, the patient tended to isolate himself, usually sitting on a chair, and await the resolution of pain. The pain failed to respond to simple analgesics, ergotamine, or amitriptylline. A lighter headache of dull nature sometimes awakened the patient in the early morning, but headache never occurred during the day. He had previously had neither migraine nor any other kind of headache. The patient had a history of snoring and sleep apnoea, which developed in middle age. He took an antihypertensive agent, antiplatelet agent and sleep medications such as zolpidem.Blood pressure was 147/93 mmHg and other vital signs were normal. Physical examination was unremarkable. There were ataxia and increased tone in right limbs with extensor planter reflex on neurological examination. The results of basic blood tests and urine analysis were normal. We found a small lesion on magnetic resonance imaging that was performed after stroke. The lesion was located in the ventrolateral portion of the midrostral upper pons (Fig. 1). The lesion did not enhance with gadolinium. Their topographic localization corresponded to the pontine reticular formation, where the neural network generating rapid eye movement (REM) sleep is presumed to be located.A polysomnograp...

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