Two Cases of Hypnic Headache

Hypnic headache is a unique headache disorder that occurs exclusively during sleep and often with "alarm-clock" consistency. It is a rare, benign, moderately severe, enduring headache syndrome that occurs in middle-aged to elderly adults and affects both sexes. The pathophysiology of hypnic headache is unknown, but its circardian periodicity and responsiveness to lithium suggest chronobiologic sleep disturbance contributing to the genesis of hypnic headache. We have recently experienced 2 cases of hypnic headache. They showed the characteristic signs of hypnic headache. We present our cases and discuss the pathophysiology of hypnic headache.