It sounds like you and I have similar reactions to supplements and I’ve been trying to figure out my insomnia lately too, which started with me taking a prescription that enhances cholinergic transmission.
So, that led me to suspect acetylcholine but it‘s confusing because in the past, things that increase acetylcholine (like mestinon) haven’t caused this… taking citi-choline did make me feel bad but I don’t remember how.
I also thought of histamines so I tried taking a weaker antihistamine (it doesn’t cross the bbb as much as diphenhydramine or hydroxyzine), cetirizine, which only makes me very slightly drowsy. For 2 nights I’ve slept better with it but I still have some trouble falling asleep initially.
My brain also feels a little calmer during the day which is helpful because I’ve had terrible brain fog.
Cetirizine is only a weak anticholinergic, so I don’t know if it’s the histamine or choline situation that it’s helping (or maybe I’m just feeling better with a little more sleep?)? It might not be the answer to my problems but we’ll see.
Lemon balm used to help me too and it supposed to increase acetylcholine (decrease its breakdown).
My thought is that maybe it’s an increase in choline (increasing methylation like mentioned) causing the problem and not acetylcholine. Or it’s histamine… Or I also liked
@Violeta ’s suggestion of tanking neurotransmitters, that makes sense to me too