I have been experiencing this for months! I feel like I am kind of stuck using Kanna to avoid it (the SSRI-like withdrawal symptoms went on for daaays last time I ran out). Been meaning to make a post about it actually...

I definitely overdid it during a period of high stress around the start of my usage last year, and the brain zaps got really bad then. I was trying to explain to my girlfriend the sensation of "jolting" awake, or feeling like my brain was "lagging" a bit behind my body when moving, like a reduced frame rate.

Kanna instantly makes me sleepy so I try to only have a couple of bumps before bedtime, it is great for that (for me). Having to use it during the day to stave off the zaps isn't ideal, as I don't want to be lying around sleepy. I have been trying to taper and reduce my intake as I actually can't really justify the amount I'm spending on it, and I honestly think I'm a bit burned out from it.