Daily stress as a trigger of migraine attacks: results of thirteen single-subject studies.

A 6-month longitudinal study examined whether migraine attacks were preceded by or occurred on stressful days. Every evening 13 patients filled out a questionnaire assessing daily stress. Analyses on single-subject level tested whether attacks occurred more often than expected by chance 3, 2, or 1 day after or on day when stress scores were in the upper third of the subject's distribution. Increased stress was generally not found for Days 2 and 3 before an attack, but often for Day 1 and on the migraine day itself. The latter findings were also significant on a group level.