The relationship between sleep and headache has been known for over a century. Sleep represents the only well documented behavioral state related to the occurrence of some headache syndrome. Liveing1 in 1873, wrote about the effect of sleep in terminating an attack of headache. Bing2 also, noted this relationship when he wrote about early morning headaches. Gans3 reported a decrease in frequency and severity of migraine attacks following selective ‘deep-sleep deprivation.’ Dreams4 leading to headache have been reported. Quite obviously, headache also finds a place in the classification of sleep disorders.5 This very important relationship between sleep and headache is the subject of this clinical review.