Headache and Sleep

Sleep is an essential biological function and a highly conserved behavior across animal evolution. During sleep, most of the body’s systems are in an anabolic state, which helps restore the immune, nervous, and muscular systems. Sleep maintains mood, enhances memory and cognitive function, and supports the endocrine and immune systems. Humans spend approximately one-quarter to one-third of their lives in the active state of sleep, allowing a considerable opportunity for overlap between normal sleep, sleep disorders, and headache. Sleep disorders occur in an estimated 50% of individuals with headache and are more prevalent in those with more severe forms of headache. Both headache and sleep are strongly influenced by external environmental factors, such as temperature and light, and more internal psychological or cognitive processes, such as thoughts, emotions or moods, or prior experiences. Sleep fragmentation, insomnia, hypersomnia, and circadian rhythm disorders all have relationships with headache. Poor sleep has been found to affect pain perception and trigger the onset and maintenance of next-day migraine in adolescent and adult patients. Sleep disorders, particularly insomnia and obstructive sleep apnea (OSA), increase the risk of transformation from episodic migraine (EM) to chronic migraine (CM). Conversely, sleep is known to relieve headache symptoms, and a significant improvement in headache can precipitate from the appropriate handling of sleep disorders. More specific correlations between headache and sleep have also been described in various primary headache disorders. For example, chronic paroxysmal hemicrania and cluster headache (CH) have strong relationships to rapid eye movement (REM) sleep, and hypnic headache (HH) occurs during non-REM sleep. Sleep-associated headache disorders are generally thought to stem from disrupted sleep. On the other hand, primary headache disorders such as migraine, CH, chronic paroxysmal hemicrania, and HH may, in turn, result in sleep disruption.