<unk>  is a medical condition in which a person develops a headache while vertical and the headache is relieved when horizontal. Previously it was often misdiagnosed as different primary headache disorders such as migraine or tension headaches. Increasing awareness of the symptom and its causes has prevented delayed or missed diagnosis.
Orthostatic headache
Cold-stimulus headache
External compression headache
Hypnic headache
Sexual headache
Tension headache
Thunderclap headache
Vascular headache