Three months of diary entries usually produces a handful of apparent patterns, and most of them will not hold up. The reason is arithmetic rather than carelessness: check enough possible triggers against enough attacks and some will line up by chance.
Reading tracking data well is mostly about knowing which apparent patterns to distrust, and the ones worth acting on are the ones that survive a specific test. Our roundup of migraine tracking apps covers collecting the data.
Medical Disclaimer
This is general information about interpreting your own records, not medical advice. Patterns you identify are hypotheses to discuss with a doctor rather than conclusions to act on alone, and no diary can diagnose anything. Any changing or worsening headache pattern needs medical assessment.
Quick Answer
Compare how often a suspected trigger appears on attack days against how often it appears on non-attack days. If the rates are similar, it is not a trigger, however strong the impression.
The Test That Matters
The useful question is not how often a trigger appeared before an attack. It is whether it appeared more often before attacks than before ordinary days.
Someone who drinks coffee every morning will find that coffee preceded every attack, because coffee preceded every single day of the year. Without the comparison against ordinary days, that looks exactly like a finding.
Doing it properly means counting four things: days with the trigger and an attack, days with the trigger and no attack, days without the trigger and an attack, and days without either. Only the comparison between those tells you anything.
This is why recording non-attack days matters so much, and why diaries that only capture attacks cannot answer trigger questions at all.
Why Apparent Patterns Mislead
Testing many things at once
Check twenty possible triggers against a limited number of attacks and some will correlate by chance alone. The more fields you log, the more false patterns you will find, which is a property of the arithmetic rather than of your record keeping.
Recall bias
Logging retrospectively after an attack means remembering what you did through the lens of looking for a cause, which reliably produces one.
Prodrome mistaken for cause
Cravings, yawning, mood change, and appetite shifts can precede an attack by hours. The food craved during prodrome looks like a trigger and may be an early symptom.
Small numbers
Four attacks is nowhere near enough to distinguish a genuine pattern from coincidence, whatever the impression at the time. Patterns need repetitions across months before they become credible.
Patterns Worth Taking Seriously
Some patterns have enough documented support that finding them in your own data is more likely to be real. Hormonal patterns around the menstrual cycle are among the best established.
Sleep disruption in either direction, too little or too much, is another with consistent evidence behind it, which is why weekend attacks are a recognized presentation.
Skipped meals and dehydration appear regularly in the literature and are simple to test since both are easy to change deliberately.
Weather sensitivity is commonly reported and the evidence is genuinely mixed, so it belongs in a middle category: plausible, hard to confirm individually, and impossible to avoid anyway. Our note on weather-triggered migraine covers that.
Start With Frequency, Not Triggers
Before looking for triggers, look at the shape of the data. Attack days per month over time is the single most useful chart, because it shows whether things are getting better or worse.
Treatment days per month sits alongside it. A rising count is clinically significant on its own and is one of the first things a doctor will want.
Duration and severity trends matter alongside those. Attacks becoming longer or more severe is a genuinely different situation from attacks becoming more frequent, and the clinical responses to each are not the same.
These trends need no statistical reasoning and answer the questions that actually change management. Our roundup of migraine journals covers recording them.
Testing a Suspected Trigger
If the comparison suggests something real and it is safely modifiable, a deliberate test beats more observation.
Change one thing at a time and hold it for long enough to cover several expected attacks. Changing three things simultaneously tells you nothing about which mattered.
Be cautious about elimination generally. Restricting foods on weak evidence narrows the diet without benefit, and repeated elimination can become its own problem. Anything involving substantial dietary change is worth discussing with a doctor first.
Our note on whether exercise triggers migraine covers a case where avoidance carries its own costs.
What Good Data Looks Like
Usable tracking data has three properties, and none of them is about how many fields you filled in.
It covers a long enough period. Several months is the practical minimum for most people, because patterns need repetitions and a month rarely contains enough attacks to distinguish signal from coincidence.
It includes ordinary days. A record containing only attacks can describe attacks but cannot compare them against anything, which rules out every trigger question before you start.
And it was recorded prospectively rather than reconstructed. Filling in three weeks from memory produces a record shaped by what you were looking for, and that shaping is invisible once it is written down as data.
Data missing any of those three can still be useful for frequency and treatment counts, which are worth having regardless. It just cannot answer questions about causes. Our roundup of sleep trackers covers passive collection.
Bringing Data to an Appointment
Summarize rather than handing over raw logs to read through. Attack days per month, treatment days per month, typical duration, and how much the attacks limited what you could do covers most of what will be asked.
Note any suspected patterns as open questions rather than as settled conclusions, which invites a proper assessment rather than a polite correction.
Bring the trend over time rather than a snapshot, since direction of travel matters more than any single month. Our note on questions to ask a neurologist covers the rest of the visit.
Migraine Pattern FAQ
How do I know if something is really a trigger?
Compare how often it appears before attacks against how often it appears before ordinary days. If both rates are similar, it is not doing anything, however convincing the impression from attack days alone.
Why do I keep finding patterns that do not hold?
Checking many possible triggers against a limited number of attacks produces coincidental matches. The more fields you track, the more false patterns appear, which is arithmetic rather than a failure of attention.
How many attacks do I need before a pattern means something?
More than a handful. Four attacks cannot distinguish a real pattern from chance, and most people need several months of consistent recording before trends become readable.
Could a food craving be a symptom rather than a trigger?
Yes, and this is a well-documented confusion. Prodrome can include cravings and appetite changes hours before pain begins, so the food eaten beforehand may have been an early symptom of an attack already underway.
Which patterns are most likely to be real?
Hormonal patterns around the menstrual cycle and sleep disruption in either direction have the strongest documented support. Skipped meals and dehydration also appear consistently and are simple to test deliberately.
Should I eliminate suspected trigger foods?
Cautiously and ideally with medical input. Restriction based on correlation alone commonly removes foods that were never causing anything, and repeated elimination narrows the diet without benefit.
What should I look at first?
Attack days per month and treatment days per month over time. Those trends require no statistical reasoning, answer what a doctor will ask, and matter more for management than any individual trigger.
When should I see a doctor about what I found?
Bring any suspected pattern to an appointment rather than acting on it alone. See a doctor promptly for any new, sudden, or severe headache, headache with neurological symptoms, or a pattern that is worsening or changing in character.
Sources
- Headache Classification Committee of the International Headache Society. The International Classification of Headache Disorders, 3rd edition. Cephalalgia. 2018;38(1):1-211. https://ichd-3.org/
- Peris F, Donoghue S, Torres F, et al. Towards improved migraine management: Determining potential trigger factors in individual patients. Cephalalgia. 2017;37(5):452-463. https://journals.sagepub.com/home/cep
- National Institute of Neurological Disorders and Stroke. Migraine. National Institutes of Health. https://www.ninds.nih.gov/health-information/disorders/migraine
Recommended Reading
See our note on wearables for migraine tracking, and what to record in a migraine diary.
For the wider picture, see our guide to how to choose migraine glasses.
