system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If weed is a depressant, why does my heart start to beat faster whenever I smoke?

Everytime I smoke weed my heart starts to beat pretty quickly. I've never been able to measure my BPM after smoking, but it at least feels like it's racing, sometimes even at an almost frightening pace. Shouldn't weed lower my pulse and BPM because it is a depressant to the body systems?
gpt
> If weed is a depressant

That's just it.  It's not a depressant.  At the high level it's a psychoactive compound - it can cross the blood brain barrier and can act on parts of the brain.  Depressants, stimulants, and hallucinogens are all psychoactive.  Weed is basically in a category of it's own since it doesn't fit into any of those categories perfectly but rather can have effects from all three in varying combinations.