Yeah Kratom and Kava can definitely help. I would focus on your primary essentials, that before meth you would most likely do on daily basis. DRINK water! your most likely dehydrated. Eat! You could most likely use some nutrients and calories. and well... Sleep will eventually come. You could go for a long walk if your not feeling up to some kind of more strenuous exercise. I like your point OP, I normally look to a wide variety of supplements and medications to aid in such things. and I could go on and on......
I would say drink and eat, and drink, then drink some more. (WATER! ofc) or i suppose stuff like Gatorade with the electrolytes will help. Your going to have depleted levels of magnesium and calcium from the meth. this is somewhat related to bruxism (jaw clenching, teeth grinding). Your brain is going to remain well, over-saturated with adrenaline basically. or more specifically it would be norepinephrine and epinephrine. My understanding is the reuptake inhibition of the dopamine in your brain will go before the other two adrenaline related neurotransmitters do. partly in my opinion why the comedown is so bad. because first all that dopamine is dropping out to recover from basically being without a surge protector on "overpower" or something like that, lol. Basically your dopamine systems in your brain are gonna be fried for a moment, and it takes a while to get rid of the epinephrine. So in my mind, i would suggest someway of further exhausting yourself with exercise or a long walk. then again, our adrenals are what can give us remarkable energy when we can be most depleted. Imagine a mother completely exhausted from many long hard days and not much sleep. then the house catches on fire or she's carrying her young when attacked by an animal or person. Or when your are "jumped" you go from being super tired to fully engaged and focused.
I'm a lil tweaked so i dont mean to ramble too much. I'm just used to taking a variety of drugs as i've stated earlier. I would say just a long walk of some sort to help promote sleepy-ness, but make sure to re-hydrate and eat! I suppose eating might help with sleepiness as your digestive system starts demanding more blood flow.
And as CFC mentioned about a hot shower/bath, opening up those blood vessels, excellent tip. I'm used to keeping cool while tweakin, but honestly during a comedown, i just wanna relax! After that.... it might just be patience......
And i just have to say, how horribly neurotoxic/ oxidative meth is. I'd recomend getting a large bottle of CoQ10 to help reverse the oxidative damage. I've come to realize all the supplements i have will only help if i actually STOP the meth, otherwise i'm just attempting to slow down something that might as well be free falling. The rapid, acute, and toxic damage cause by meth is unfathomable. Especially when you start to binge and add sleep deprivation to the mix. Meth blocks a fail safe mechanism in our brains that if a neurotransmitter like dopamine gets to high, into toxic levels, the brain will start re-absorbing it so its no longer toxic. But with meth that mechanism is blocked, and thus the high and relentless comedowns and sleeplessness with anxiety etc..... There are most likely lots of over the counter herbs and medicine that will help. however, i realize that is irrelevant in this example.
Best of luck to ya, I'm done rambling
as always, if i have provided misinformation, i stand corrected. Maybe i have just used horrible grammar and suggested the wrong thing, or maybe i just straight up am wrong. but thats somewhat my understanding of this demon