There were probably fungi that could have produced hallucinations, or plants mixed in a certain way that may have gone extinct since then. People back then certainly could have imagined things when under the influence especially given their limited knowledge on the laws governing our existence. It could be fun, and fun is the goal.
Not sure how you think blurred sight and drowsiness could simulate this, or what that comment contributed to this discussion. Don’t want the visions? Don’t mix the potions.