Hypnic Headache

BackgroundHypnic headache (HH) is a rare primary headache characterized by strictly sleep-related headache attacks. MethodsThis paper reviews the pertinent literature on HH. ResultsDisease information is mainly based on case reports and small case series (around 250 cases) published since its first description in 1988 by Raskin. HH usually starts over the age of 50. Frequency of patients with HH among patients consulting tertiary headache care centers is estimated from 0.07% to 0.35%, but exact prevalence of HH is unknown. Diagnostic criteria were recently updated by the third edition of the International Classification of Headache Disorders beta version (ICHD-3). Recent data suggest a possible hypothalamic involvement. ConclusionDevelopment of clinical research is needed to better understand the mechanisms of HH and to optimize treatment. Evidence for treatment data are missing, so treatment recommendations are based only on case reports or smaller open case series and reflect clinical experience. Caffeine can be used first line for acute treatment. Lithium and caffeine are possibly effective in prevention.