Our so-called biological clock is the collective name given to a range of interacting molecules that regulate our sleep-wakefulness cycle and the bodily and behavioral changes that go with it.
New research examines the link between this clock - which is also regulated genetically - and the risk of developing migraines.
As the authors explain, their research was prompted by previous studies suggesting that people with mood disorders often have symptoms that signal a disruption of their circadian rhythm.
Additionally, other studies referenced by the authors have pointed to a link between mood disorders and certain variations in the genes associated with the circadian rhythm, as well as to a genetic link between mood disorders and migraine.
Stressors have been shown to trigger migraines by disrupting the body's rhythmicity, and all of this existing evidence made the researchers wonder whether circadian genes might also play a role in the development of migraines.
Studying migraines, stress, and clock genes
Baksa and colleagues recruited a total of 2,349 participants from Budapest and Manchester in the United Kingdom and asked them to report on whether or not they had migraines using the ID-Migraine Questionnaire.
The CLOCK gene is the main genetic component of the circadian clock. Therefore, the researchers zoomed in on it, screening the participants for two single nucleotide polymorphisms, or variants, of the CLOCK gene.
The participants were also asked to fill in a financial questionnaire, and the researchers defined chronic stress in relation to financial worries.
Baksa and team tested the effects of the CLOCK gene variants on migraine statistically by applying logistic regression models and adjusting the analysis for population, gender, and age.
At first, the study found no link between the CLOCK gene variants and migraine, but when they added financial stress into the mix, the results changed.
Stress raises migraine risk by 20 percent
People who were having financial difficulties were 20 percent more likely to have migraines if they also had the two CLOCK genetic variants.
Baksa explains the findings, saying, "We were able to show that stress - represented by financial hardship - led to an increase in migraine in those who have a particular gene variant."
"This work does not show what causes migraine - there is no single cause - but it does show that both stress and genetics have an effect," he adds.
"The strength of our study is that we saw the same effect in two independent study groups, in Budapest and Manchester, so we think it is a real effect. [...] Our results shed light on one specific mechanism that may contribute to migraine. What it does mean is that for many people, the stress caused by financial worries can physically affect you."
Prof. Andreas Reif, of the University Hospital in Frankfurt, Germany, also weighs in on the findings. He says, "[The] study demonstrates how an environmental risk factor exerts its effect only in the presence of a given genetic risk factor. This has not been done to a great extent in migraine, making this study an exciting new lead."
"What we need to do now is to see if other circadian gene variants in association with different stress factors cause the same effect," concludes Baksa.