Hi there! In the strict sense, CBD is a psychoactive drug: It is a chemical substance that can change perception, behavior and mood. However, when labeling a substance psychoactive, we tend to think of more obvious effects when taken, such as those caused by THC, alcohol or benzodiazepines. But did you know that chamomile tea is mildly psychoactive? Similarly, CBD works as a sedative, but the change is subtle for most.
Several recently published studies suggest that CBD reduces depression and anxiety symptoms by mimicking serotonin's action at the same receptor (5-HT1A) that SSRIs work on. In two studies, both published just this year, researchers administered CBD to rats, which then resulted in significant reductions in anxiety- and depression-related behaviors. However, when the rats were pre-treated with an agent that blocks the 5-HT1A receptor, CBD did not affect their behaviors, thus indicating that CBD's interaction with the 5-HT1A receptor was the affecting mechanism. https://www.ncbi.nlm.nih.gov/pubmed/30157131 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2697769/
I hope this helps!