Unexpected Daily Events May Influence Migraine Risk

Subtle shifts in routine could help predict short term vulnerability in migraine

A new study suggests that a day filled with unexpected or unusual experiences may raise short term migraine risk. The findings show that “surprisal,” a measure of how atypical someone’s day is, could be used to forecast attacks more accurately than traditional trigger checklists.

Study Details

Researchers from Harvard Medical School analyzed data from 109 adults diagnosed with migraine with or without aura. Participants recorded potential triggers twice daily over 28 days between April 2021 and December 2024. Most were women with a median age of 35 and experienced 4 to 14 headache days per month.

The study focused on surprisal an information theory concept that measures how out-of-the-ordinary a person’s daily experiences are, rather than examining single triggers like stress, light, or sleep changes. This approach reflects how real life migraine triggers often interact instead of acting alone.

Methodology

Participants logged their exposures (sleep quality, stress, diet, sensory triggers, and other daily experiences) every morning and evening. Using these entries, researchers calculated a within-person surprisal score based on how unusual that day’s experiences were compared to their own typical patterns.

Migraine occurrence over the next 12 and 24 hours was recorded as the main outcome. Analysis included both fixed-effects and random-effects models to account for individual variability.

Key Findings

• Higher surprisal scores were linked to a significantly increased risk of a migraine attack in the next 12 hours (OR 1.86) and 24 hours (OR 2.15).
• When individual variability was considered, the association persisted, though slightly reduced.
• Surprisal provided meaningful predictive value, supporting the idea that combinations of subtle changes in daily life may matter more than any single trigger.
• The association was stronger over 24 hours than 12 hours, suggesting that effects may accumulate rather than act instantly.
• When recent surprisal scores were already high, the impact of new surprisal was weaker or reversed, hinting at possible adaptation or regulatory effects.

Implications for Practice

For people with migraine

This study suggests that the “unexpectedness” of a day changes in routine, unusual stressors, or atypical sensory exposures may matter more than classic standalone triggers. Tracking patterns and fluctuations, not just fixed triggers, may help patients understand their own vulnerability in real time.

For clinicians

Surprisal may offer a more accurate and individualized way to predict short term migraine risk. It shifts thinking from static trigger lists toward dynamic, context-aware forecasting. Incorporating surprisal-based tools into digital diaries or mobile health apps could enhance proactive management, early intervention, and counseling.