The first time I’ve ever heard the “dark night of the soul” referred to as spiritual depression. “Dark night of the soul” customarily describes part of the
via negativa approach to mystical experience in the Christian traditions, e.g. St John of the Cross. Aunque es de noche...
Depression sounds like something that just takes a pill to fix...a disease of the brain. The via negativa is most assuredly not a brain sort of thing...