• headache;
  • sleep test;
  • pathophysiology;
  • polysomnography;
  • treatment

Hypnic headache syndrome is an unusual chronic headache that usually begins after age 60 years and occurs exclusively during sleep. Despite the relationship between the headache and sleep, no formal sleep evaluation with overnight polysomnography has been reported for this syndrome. Three patients with long-standing hypnic headache underwent overnight polysomnography. The results were quite variable, ranging from normal to marked sleep insufficiency. A hypnic headache was captured in one patient arising out of rapid eye movement sleep at a time of severe oxygen desaturation. Formal sleep evaluation should be considered in patients with hypnic headache because there may be pathophysiologic and therapeutic implications.