[Hypnic headache: characteristics of a series of 13 new cases and proposal for modification of the diagnostic criteria].

Introduction: Hypnic headache is a rare condition, since less than 150 cases have been reported to date. The second edition of the International Headache Classification (IHC2) has set out the diagnostic criteria of this condition, although some of them can be considered excessively strict.

Aims: To present a series of 13 new cases of hypnic headache that were dealt with in the headache unit of a tertiary hospital and to analyse how well they fit the diagnostic criteria of the IHC2.