I do too, never had a headache with it. The first time it happened to me I was in my early forties. I was all alone at an overnight shift at work, and wondered if pulsating rainbows that were impossible to read through were my future. That time it only lasted about 25 minutes, and a quick Google let me know what was going on.
I still get them about once every two weeks or so. I don’t really have a choice when they start showing up, and will tell my team I will be useless for anything that requires reading for the next 35-45 minutes.