Does chronic fatigue *cause* or just accompany migraine days?

i swear i tracked everything: no red meat, skipped caffeine for a week, slept 9 hours last night… and still got hit. it was worse than expected even though my sleep quality felt good and the barometric pressure was normal. i’m kinda stumped on whether we talk about fatigue as just another symptom/prodrome thing when it might actually be part of the cycle itself? or is there some deeper link i’m missing b/w chronic tiredness and trigger severity. fwiw how do others separate those?