I am not depressed, but I definitely feel a lot of what this video from Andy Stapleton discusses:
I have certainly experienced the odd stutter-step ending of the program, which never brings a single day or moment when you are really done. There is such a moment, but it is mundane, private, and undramatic — probably the last time you make a formatting correction for the unknown administrator who reviews your dissertation for conformity to writing standards like which page numbers in the front matter are Roman numerals. That creates an odd sense of the thing being unfinished, even when there is nothing left to do.
The points about needing to prove yourself in the job market after finishing, as well as anxiety about whether a PhD was necessary, are also familiar from my recent thinking.
I wouldn’t say the video provides any useful and non-obvious advice, but reading within the broad category of writing by current and recent PhD students actually has immense psychological value by demonstrating the reality of shared experience and shared struggle, engaging about all the things we didn’t known when we began and (even more juicily and importantly) all the things your university will lie to you about to keep their business model going. A post by Bret Devereaux is a fine example of the genre, and was discussed here before.