All of the following are symptoms associated with hallucinogen ingestion except for which?

Hallucinogens are a class of drugs known for their ability to alter perception, mood, and various cognitive processes. Common symptoms of hallucinogen ingestion include visual or auditory hallucinations, heightened sensory perception, extreme mood changes, anxiety, and sometimes nausea.

Sleepiness, however, is not typically associated with hallucinogen use. Instead, users often experience increased energy or heightened alertness. This makes sleepiness an unlikely symptom to arise from hallucinogen ingestion, distinguishing it from the other symptoms listed.

In contrast, hallucinations, anxiety, and nausea are all well-documented effects of consuming hallucinogenic substances. By identifying sleepiness as the outlier, one can better understand the typical effects of hallucinogens and the range of experiences an individual might undergo when using these substances.