I once ordered a kratom extract powder from some website many years ago, while on a quest for novel ways for my friends and I to get high. After calculating the suggested dosage, and swallowing an uncomfortably large number of gel caps filled with the stuff one Friday evening, we each experienced a sedated, euphoric effect.
The shocking part for us was during the next day and a bit of the day after, we found ourselves unable to perform basic math, and reasoning in general felt fuzzy. Thankfully, by Monday, we were able to function normally. We came to the common conclusion that this is a truly stupefying substance in the proper sense of the word, and that usage should be avoided if you have anything important to think about in the next several days.