Shift work, headache, and migraine in a large cohort of Dutch nurses.

OBJECTIVE: Shift work is common in healthcare and may contribute to headache disorders through mechanisms such as circadian disruption and sleep disturbance. However, evidence from large prospective cohort studies remains limited. This study investigated the associations between shift work and headache and migraine in a cohort of Dutch nurses. METHODS: Participants completed questionnaires in 2011 (n = 59,768) and 2017 (n = 37,713), reporting headache, migraine, work history, sleep problems, and lifestyle factors. Headache and migraine were assessed using the validated Headache Impact Test (HIT-6) and ID-Migraine questionnaires. Associations between shift work and the prevalence of headache or migraine at baseline and follow-up were examined using Poisson regression with robust variance to directly estimate relative risks. Additional analyses examined current shift work status and shift work duration. RESULTS: Ever shift work was associated with a higher prevalence of headache at baseline (relative risk = 1.04, 95% confidence interval: 1.01 to 1.07), although this association attenuated after adjustment for sleep problems (relative risk = 1.01, 95% confidence interval: 0.98 to 1.04). For migraine, ever shift work was associated with a higher prevalence at follow-up (relative risk = 1.13, 95% confidence interval: 1.02 to 1.26), whereas no association was found at baseline. Current shift work was not consistently associated with headache or migraine. CONCLUSIONS: Ever shift work was associated with a small increase in the prevalence of migraine. Associations with headache attenuated after adjustment for sleep problems. No consistent associations were observed for current shift work.