According to a meta-analysis of all available studies, both migraine and cluster headaches are strongly associated with the internal clock regulating body processes called the circadian system.1✅ JOURNAL REFERENCE
All migraine and cluster headache studies that involved circadian features were included in the meta-analysis. Information on headache timing throughout the day as well as throughout the year was included and also studies on if genes linked to the circadian clock are more commonly found in individuals suffering from these headaches.
Studies on migraine and cluster headaches and hormones linked to the circadian system such as melatonin and cortisol were also examined.
The data indicate that both of these headache conditions are strongly circadian at multiple levels, particularly cluster headaches. This reinforces the significance of the hypothalamus, the brain area where the primary biological clock is located, and its role in migraine and cluster headaches.
A circadian pattern of cluster headache attacks was observed in 71% of individuals, with attacks peaking late at night till early in the morning. More attacks were experienced in the spring and fall throughout the year. Cluster headache was linked to 2 key circadian genes on the genetic level, and 5 of the 9 genes that increase the chance of experiencing cluster headache are genes that have a circadian pattern.
Individuals suffering from cluster headaches also had lower melatonin levels and higher cortisol levels compared to individuals not having cluster headaches.
A circadian pattern of migraine attacks was seen in 50% of individuals. Although the peak for attacks throughout the day ranged widely from late in the morning till early in the evening, a circadian low point was seen throughout the night when hardly any attacks took place. Migraine was also related to 2 core circadian genes, and 110 of the 168 genes related to migraine were genes that have a circadian pattern.
Individuals having migraine had lower urine levels of melatonin compared to individuals not having migraine. Levels of melatonin were also lower throughout a migraine attack.
These results raise the possibility of using circadian-based therapies for headache disorders. This could include both therapies based on the circadian rhythm and therapies that result in circadian changes.
A study limitation was that there was no information on circadian cycle influencing factors, which include medications, circadian rhythm issues like night shift work, or other disorders like bipolar disorder.
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