Yep, I realized mine were caused by looking out the window while I brushed my teeth in the morning. One day it was really bright outside and really dark inside and the migraine started almost immediately. More than a year and I keep the blinds drawn while I'm in the bathroom in the morning and not a single migraine!
This is interesting. I frequently had them triggered by riding BART in the late afternoons in the winter, sun beating in through the dirty windows. Going through the tube (dark) and emerging in Oakland (raised track, clear view of the sky on both sides) had a double-digit % chance of giving me a migraine if my eyes were open at one point.
I can get them triggered by riding in a car in similar conditions, too, especially if the windows aren't squeaky clean. I frequently wonder why that is, something about the remaining spectrum of visible light when the windows are dirty?
Reminds me of wearing non-prescription sunglasses despite having myopia. It feels like the blurring of the world is due to the glasses, even though they're actually only blocking some of the light rather than distorting it.
