[Description of a series of cases of hypnic headache. Differentiation between sexes].

Hypnic headache is an infrequent type of primary headache characterised by appearing almost exclusively during sleep and by waking the patient up. The pain is dull (generally bilateral), is not associated to autonomic signs and usually appears from the age of 50 onwards. A 10-year prospective study was conducted which describes the patients with hypnic headache who were attended in a specialised headache clinic. Data collected include demographic variables, the characteristics of the pain and response to treatment. Data from males and from females were compared. Twenty-four patients were diagnosed with hypnic headache: 15 females and 9 males. There were no differences between sexes as regards the age at onset of the pain, the time elapsed until diagnosis, the number of episodes per month or the amount of time the pain lasted. The males reported a more intense pain (measured by means of the analogical visual scale) than the females. Neither were there any differences in terms of the presence of arterial hypertension or obstructive sleep apnoea syndrome. Response to different symptomatic and preventive treatments was scarce and with no differences between sexes. The pain in hypnic headaches is more intense in males, although this needs to be corroborated in longer series. Further advances need to be made in the pathophysiology of this kind of headache so as to be able to find more efficient preventive pharmacological agents.