I have extensive experience with pharmaceutical anti-depressants and with psilocybin.

It's not the introspection that causes psilocybin's anti-depressant quality. Mood and improves, and phantom pain diminishes by about 12-24 hours, regardless of the qualities of the trip, and continues to rise for a couple of days. Even if the trip is relatively non-descript, or is difficult, the internal change is still very clear.

A euphoric trip overshadows this change, obviously.