system
Given the following post, respond as if you're commenting on Reddit:
human
Why do we get depressed without even knowing the cause?

So I just got to thinking. With all the amazing things our body can handle on its own, and signal to our brain. Ie. If you hurt yourself, you will be able to tell where it hurts, and you make out the when and where.
So how come mental health is so tricky for the body to mediate? How is it some people can go around for a bigger part of their lives feeling depressed without knowing why. Why is it the brain "neglects" why you are feeling bad ?
gpt
Experimental Psychologist Wilhelm Wundt established in his book *Principles of Physiological Psychology* that the physical reactions of the body trigger a reaction and trigger your mind, it doesn't start in the mind.  This gets a little complex, so I'll try to break it down:  You have an anxiety response, which makes you react, and also tells your mind that there is a problem, and then your mind quickly searches for that problem.  This is all integrated very quickly and normally completely unconscious, so you'll have a reflex action (fight, run, whatever) and your mind quickly follows. This was great 50,000 years ago when you needed to react quickly to a sabre-toothed tiger, but now it can be dysfunctional.

Essentially, *something* in your body causes cortisol and/or adrenaline to spike, which tells your mind there is a problem.  Your mind quickly tries to figure out the problem.  For most people, there is no realization that the reaction is starting in the body.  So in practice, this means that maybe you had too much sugar in your coffee, or you had an extra cigarette, or maybe it's a random physiological event (or in the case of major depression, it starts when you wake up in the morning), which causes a spike in heart rate and cortisol/adrenaline, etc.  This tells your mind that there is a problem, and your mind then searches your memory to see what you should be worried about.  Then you find it, your boss looked at you funny the other day, or your car needs to be repaired, or you are having marital problems, or maybe you're just generally not happy with your life, whatever.  So you ruminate and catastrophize on this problem that your body told you to find.  The rumination then causes more stress hormones to build up, and you spiral in a reinforcing loop.   All the while you never noticed that it started with a physical feeling in your body.  

So, the physical reaction causes you to search for a problem in your life to fixate on, which you then do, which makes it worse, and this can lead to and/or reinforce depression.  Obviously thinking about a bad or depressing event can also set off the physical reaction, creating this feedback loop - you're dealing with something bad, you focus on it, it causes the release of stress hormones, which causes you to continue to focus on the bad, and you get stuck in that feedback loop as well.

Using things like Yoga or meditation to become aware of the physical feelings of stress and anxiety have been shown to teach people how to disconnect this feedback loop.  You notice the physical feelings of stress or anxiety, and instead of searching your mind to see why you should be depressed, you short circuit the process before it starts. Psychologist Aaron Beck also addresses this in most of his work. 

It's not so much that mental health is tricky for the body to mediate, it's that our culture, and probably the vast majority of cultures, do no education on emotion regulation and human mental health.