The analysis was published in the online edition of Neurology, the official journal of the American Academy of Neurology. All cluster headache and migraine studies that have circadian aspects were included in the meta-analysis.
These include studies of whether genes associated with the circadian clock are more prevalent in people with these headaches as well as information on the timing of headaches throughout the day and year. The researchers also looked at studies on cluster headaches and migraines and hormones related to the circadian system, including cortisol and melatonin.
“The data suggest that both of these headache disorders are highly circadian on many levels, especially cluster headaches,” said study author Mark Joseph Barish, MD, PhD, of the University of Texas Health Science Center at Houston, Texas. American Academy of Neurology.
“This reinforces the importance of the hypothalamus – the region of the brain that houses the primary biological clock – and its role in cluster headaches and migraines. It also raises the question of the genetics of triggers such as sleep changes that trigger migraines.” known as triggers and signals to the body’s circadian rhythm.”
For cluster headaches, a meta-analysis found a circadian pattern of headache attacks in 71% of people. The attacks peaked from the late hours of the night to the early hours of the morning. During the year, people had more attacks in the spring and autumn.
At the genetic level, cluster headache was associated with two core circadian genes, and five of the nine genes that increase the likelihood of having cluster headache are genes with a circadian pattern of expression. People with cluster headaches have lower cortisol levels and melatonin levels than people without cluster headaches.
For migraine, a meta-analysis showed a circadian pattern of attacks in 50% of people. While the peak for attacks during the day was broad, from late morning to early evening, there was a circadian low point during the night when few attacks occurred.
Migraine was also associated with two core circadian genes, and 110 of the 168 genes associated with migraine were genes with circadian patterns of expression. People with migraines had lower levels of melatonin in their urine than people without migraines.
In addition, melatonin levels were lower during a migraine attack.
“This can include both treatments based on circadian rhythms — such as taking medications at certain times of the day — and treatments that cause circadian changes, which some medications can do.”
A limitation of the study was that the researchers did not have information about factors that can affect the circadian cycle, such as medications, other disorders such as bipolar disorder or circadian rhythm issues such as night shift work.