I stumbled upon a very interesting article about depression not being a disease but a part of the fight/flight/immobilization response.
Excerpts from the article:
Immobilization has an important role. It dulls pain and makes us feel disconnected. Think of a rabbit hanging limply in the fox’s mouth: that rabbit is shutting down so it won’t suffer too badly when the fox eats it. And the immobilization response also has a metabolic effect, slowing the metabolism and switching the body to ketosis. Some doctors speculate that this metabolic state could help healing in severe illness.
In humans, people often describe feeling “out of their bodies” during traumatic events, which has a defensive effect of cushioning the emotional shock. This is important because some things are so terrible, we don’t want people to be fully present when they happen.
So the immobilization response is a key part of the biological defense, but it is ideally designed to be short term. Either the metabolic shut down preserves the organism, i.e. the rabbit gets away, or the organism dies and the fox eats the rabbit.
But if the threat continues indefinitely and there is no way to fight or flee, the immobilization response continues. And since the response also changes brain activity, it impacts how people’s emotions and their ability to solve problems. People feel like they can’t get moving physically or mentally, they feel hopeless and helpless. That’s depression.
According to Porges, what we call depression is the cluster of emotional and cognitive symptoms that sits on top of a physiological platform in the immobilization response. It’s a strategy meant to help us survive; the body is trying to save us. Depression happens for a fundamentally good reason.
And that changes everything. When people who are depressed learn that they are not damaged, but have a good biological system that is trying to help them survive, they begin to see themselves differently. After all, depression is notorious for the feelings of hopelessness and helplessness. But if depression is an active defense strategy, people may recognize they are not quite so helpless as they thought.
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.
@El_Capitan_Nemo, I thought that could be an interesting lead for fields targeting depression and anxiety.
And, for anyone stuck in this immobilization response, this could be useful knowledge 
