system
Given the following post, respond as if you're commenting on Reddit:
human
What in our brains causes feelings of hopelessness associated with suicide?

What about depression causes people to have the "hopeless" feeling that pushes so many people to suicide? Why don't we feel this while we're happy and why would our own brains be so easily led to killing itself despite the common belief while happy that suicide doesn't make sense?
gpt
Depression likely has something to do with serotonin. The most common treatments are SSRIs, which increase levels of serotonin in the brain. 

That said, mechanisms behind depression aren't fully understood. There are likely significant psychological factors as well.