The association between shift work and treatment-seeking migraine in Denmark.

In Europe, the one-year prevalence of migraine is 14.9% and migraine is on the top-10 list of leading causes of years lost to disability. Sleep disturbances and irregular daily routines are considered triggers of migraine and these factors are well-known consequences of shift work. We studied the association between treatment-seeking migraine and shift work, categorised as fixed evening work, fixed night work and variable working hours with and without night work in a Danish working population of 5872 participants. When compared with fixed day workers, only participants with fixed evening work were found to have significantly increased odds of reporting treatment-seeking migraine after adjustment for socio-demographic and behavioural covariates (OR = 1.56; 95% CI 1.05-2.32). Participants with seniority of 10 years or more notably accounted for this association. Due to the cross-sectional design, selection mechanisms may have biased the results. Practitioner Summary: The study showed higher odds of treatment-seeking migraine among evening workers even when taking a range of potential confounders into account. Due to the cross-sectional design, we cannot draw any causal inferences, but potential mechanisms underlying the present study are discussed, with an emphasis on possible selection into evening work.