Migraine, as compared to other headaches, is worse during midnight-sun summer than during polar night. A questionnaire study in an Arctic population

Objective.-To investigate potential seasonal variation of migraine and othe r headaches in an Arctic population where light conditions are extreme duri ng both winter and summer. Background.-Due to the immense seasonal variation in sunlight, focus on sea sonal migraine variation in a population living in an Arctic area is intere sting even from a theoretical point of view. Methods.-Northern Norway comprises the three Norwegian counties north of th e Arctic Circle. There are three neurology centers in this region, which pr ovide service for approximately half a million people, During a 2-year peri od, 1403 patients (0.3% of the population) were referred to these centers f or a specialist assessment of their headache. A questionnaire was mailed to all these patients; the questionnaire included questions on headache chara cteristics to make it possible to identify migraine according to the Intern ational Headache Society criteria. Questions on seasonal variation of heada che were also included. Results.-One thousand fifty-two patients (75%) returned the questionnaire. Nineteen percent reported that their headaches clearly did vary with season ; 11% experienced more headache during polar night, while 7% had more sympt oms during midnight sun season. When the migraine and nonmigraine groups we re compared, significant differences were demonstrated. Patients with nonmi grainous headache were more likely to have increased headaches during the d ark winter season, while patients with migraine experienced more headache d uring the summer (P =.002). Conclusions.-Patients with migraine were more likely to have headache durin g the bright Arctic summer season, and this distinguishes migraine from oth er headaches in this study. This observation may pertain to the increased l ight sensitivity and recently demonstrated cortical hyperexcitability in pa tients with migraine, and may perhaps suggest a role of the hypothalamus an d/or melatonin secretion in migraine pathophysiology.