**Abstract**

Sleep disorders are closely intertwined with different kinds of headache disorders. In some forms of headaches, this association is profound, such as in hypnic headache, where headaches only occur during sleep, or in cluster headache, which has connection to the REM sleep. In other headaches, the association with sleep is more subtle, but nevertheless, very relevant–for instance in migraine, where sleep deprivation or excessive sleep may act as a trigger for migraine, while sleep has a curative effect on the migraine attack. This chapter focuses in the relationship between sleep disorders and headaches focusing on the five primary forms of headaches: migraine, tension-type headache, paroxysmal hemicrania, hypnic headache, and secondary form of headaches such as obstructive-sleep-apnea-related headaches and medication overuse headaches (MOH).

**Keywords:** sleep, headaches, migraines, insomnia, sleep deprivation

## **1. Introduction**

The association between headaches and sleep is well known for more than 100 years [1]. Some headaches emerge from specific sleep stages, other headaches originate from nonspecific sleep stages, and finally some are triggered by insufficient sleep or over-sleeping and are relieved by sleep. Changes in sleep pattern is a known factor that predisposes and perpetuates headaches in an acute or chronic fashion. Sleep disorders are associated with both, primary headache syndromes such as migraines, tension-type headaches, cluster headaches, hypnic headaches, and secondary headache disorders such as headaches-on-awakening, and MOH [2]. Primary headaches are headaches where pain and associated features such as nausea or light sensitivity are the illness, and secondary headaches are headaches that result from an underlying medical disorder. The number of sleep disorders associated with headaches is also vast, such as OSA, insomnia, RLS, etc. [3]. In general, at times, more than one type of sleep disorder may coexist in a single patient, and the same applies to headache disorders.
