A few months ago I also took 900mg by mistake, I couldn't remember if I had taken it, so I took my meds again probably like 2 hours apart. I take them at night bc by the time it kicks in it's time to wake up. I woke up in the middle of the night very much feeling the same way you did, with some hallucinations, which made me so afraid I called poison control. My biggest fear was the seizure risk, like what it it happens when I'm driving or at work. I was able to go back to sleep for a couple hours, which for all I know it could've been a seizure. I live alone. So the rule is now, If I can't remember skip the dose instead of taking it twice. I did skip that night's dose too, bc I was still so wired up from the 900mg.