If depression is the emotional expression of the immobilization response, then the solution is to move out of that state of defense. Porges believes it is not enough to simply remove the threat. Rather, the nervous system has to detect robust signals of safety to bring the social state back online. The best way to do that? Social connection.
For people who don’t prefer social connection, I’ve seen that exercise works well
Edit: just want to highlight that polyvagal theory, the main point behind this article, is unsubstantiated thus far
Been trying for years, working with a psychiatrist and therapist. They can’t solve the situational causes though
Then I wish you luck.