They're confusing and a total *****. My last big one didn't hit me for like 24 hours. Slipped on some ice and bounced my head off concrete one night, still ran my little errand and came home and went to bed. Next day I was waiting for my girlfriend to get off work and stopped at a nearby bar. Halfway through one drink, the entire room started melting and I had to cover my one eye to call an Uber. Probably had on and off symptoms for a month after, from light sensitivity to nausea to irritability.
Yeah, its insane just how little we know about how they affect the human mind. Then again, it's hard to convince someone to allow you to play around inside your head while you're alive, and when you're dead, it's hard to see the impact.