The brain is an bodily system, just like any other. Disease can strike its workings and doctors can help with modern science.
That said, we're still understanding how the brain works. One recent study showed that depression often has an associated and underlying, undiagnosed, sleep disorder [1]. Treat the depression without treating the sleep disorder and the depression comes back. FYI: This work has not been published yet.
Given that scientists have just figured out that sleep clears the brain of toxins [2], similar to the lymphatic system clearing the rest of the body of waste, these results shouldn't be surprising. We don't know the exactly reasons why people get depressed, but the evidence is clear. Depression has a root physical cause just like any other illness.
N=1, but yeah fixing my sleep pattern, while getting a work an exercise routine has pushed my depression into "remission" for the past two years. The problem was, I couldn't do all that when I was depressed, so I used Lexapro as a band-aid, I went on it for 4 months to stabilise while I sorted the other stuff out. Now I'm doing great! I'm wary of going on the medication for long periods of time, as the last time I was on it for more than 6 months the mental and physical side effects became horrendous. But it did help, and I'm glad I'm here today :)
That said, we're still understanding how the brain works. One recent study showed that depression often has an associated and underlying, undiagnosed, sleep disorder [1]. Treat the depression without treating the sleep disorder and the depression comes back. FYI: This work has not been published yet.
Given that scientists have just figured out that sleep clears the brain of toxins [2], similar to the lymphatic system clearing the rest of the body of waste, these results shouldn't be surprising. We don't know the exactly reasons why people get depressed, but the evidence is clear. Depression has a root physical cause just like any other illness.
[1] http://www.nytimes.com/2013/11/19/health/treating-insomnia-t...
[2] http://news.sciencemag.org/brain-behavior/2013/10/sleep-ulti...