[AnthonBerg]

That’s a good question. I’m not sure what the implications are yet.

It’s a complex system of cellular receptors and substances that activate them, and the receptors can become upregulated and downregulated. Histamine is also a pro-inflammatory substance.

I do better with my insomnia and autoimmune disorders if I am… attentive towards carbohydrate intake. Less sugar is better, slower carbohydrates are better. (I can reliably induce an insomnia awakening at precisely 05:30 by eating dessert after dinner. I’m not yet sure why or how exactly, but the histamine connection makes sense. It also has to do with cortisol I believe.) However, I am also more alert and sharp if I get enough carbs – including sugar. At the right time of day.

Here’s my source for histamine being involved in glucose metabolism: Histamine metabolism in diabetes mellitus and vascular disease, dr. Dalvir Gill’s 1991 PhD thesis: https://discovery.ucl.ac.uk/id/eprint/10120875/

Regarding histamine as an alertness neurotransmitter, I point to early antihistamine medication being sedative. This is because early antihistamines were molecules small enough to cross the blood-brain barrier. Histamine receptors in the brain regulate alertness. As well as the hunger response, interestingly. Old allergy meds make you hungry and then you pass out.

[sparrow98]

It seems simple carb diet leads to rapid spikes and crashes in blood sugar, which can cause energy level fluctuation and impact alertness and sleepiness. On the other hand, slow carb diet provides better blood sugar control and many other benefits. Also, slow carb diet usually opts for whole, unprocessed food, which links back to Zelphyr's point 1 as well. Fascinating.