Hypnic headache: a case report with polysomnography.

We report on a case of nocturnal headache attacks fulfilling the criteria for hypnic headache syndrome. Using an overnight polysomnography, one nocturnal headache attack was captured during the REM phase of sleep. Quality of sleep was poor with desaturation episodes. However, the hypnic headache attack was not associated with oxygen desaturation. This additional case supports the view of a relationship between the hypnic headache syndrome and the REM sleep stage. Lithium therapy decreased the intensity and frequency of headache attacks.