This is going to be one of my long ones folks. As anyone reading the responseS here can see there are different forms of Depression, and different causes.
i have battled depression since i was 11 years old. After my parents split up. Situational depression. But it may have been inevitable i'd have some form and degree of it.
i once filled out a questionnaire in a psychology book about factors that play into it. There was no doubt that 4 of the 5 main factors were at play in my life including possible Genetics and modeling. Both parents had difficult childhoods and tended toward pessimistic views of life tho they had their moments of joy. i also have SAD, Seasonal Affective Disorder which has to do with how much full spectrum light you get. Living in Climates with frequently overcast skies (whether from natural weather or urban smog) can contribute to depression. Stormy days don't impact me much if there is actual precipitation resulting but the days on end of grey skies (as in NJ when Mom moved me north) that get to me. Another reason living in dry rural climate good for me.
i can't recall all the ones now, just that the only one i was unsure if i had is the 'chemical imbalance'. However, they've yet to develop a physical test that can confirm that, what is more last info i've seen---they can't be entirely sure that the imbalance is spontaneous and pre-existing from birth, or if life events impact the chemical balance. Given what they have verified about the brain---i'd tend to think that our lives impact the brain. That doesn't mean that meds can't help, temporarily or long term. That is a choice each person needs to make for themselves. Actor, writer, blogger Wil Wheaton of Star Trek has been a really good spokesman and advocate as he suffers both anxiety and depression. He encourages those who do take meds (like himself) to be sure they are completely honest with their provider about any negative side effects or feelings it isn't help enough.
For myself i couldn't go that route. 1) i tend to get anomalous reactions to even OTC meds. 2) i had a sister who was diagnosed as Schizoid while in the Navy. i was 13 at the time. Her almost zombie like demeanor and one statement she made made me very leery of psychotropic meds. As the years passed things came to light that she may have been misdiagnosed or worse (story for another time). Two of us four sisters have studied psych and we both came to feel that if anything she had a Disassociative Disorder. Docs claimed she talked in 'word salad', but i generally knew what she was trying express.
The upsetting statement? A new patient down the hall was screaming. My sister looked at me and said: 'She's doing what all of us here are doing on the inside, we'd scream aloud if we could.' That experience of visiting her was also why tho i open to talk therapy i was resistant to hospitalization as well as meds, even when i had spells of the depression immobilizing me for short periods.
So...i self medicated with alcohol for most of my suicidal years. (first attempt at 13, lastone just months shy of 28) but not on a daily basis--a couple of times a year i'd drink enough to close the thought machine down for night so i didn't even dream. Once i started getting a handle on it i used meditation as sleep aid on most nights and only at times of added 'situational' issues (like a divorce, grieving a death) would i use a pill form sleep aid for a night or two because if i could get good sleep i could get a grip. Always surprised me how quick and willing most docs were to want to prescribe both sleep aids and anti-depressants long term. Also bothers me how many GP's do not pay attention to other meds with a side-effect of 'suicidal ideation' and will prescribe them to people like me who have made clear they have a history with depression and suicidal ideation.
What did i use instead of meds, because it has never totally left me?
Depends on the trigger:
When situational i apply my problem solving skills to resolve things, disarm the trigger as it were.
When SAD related, i try to give myself the same compassion i give others. i don't demand more than basics of myself if it extends more than day or two. Also remind myself it is temporary.
Fear and worry over state of world---i search out stories that provide hope and balance.
When grief-related (happening more often as those both i and loved ones age)--i actually face it, full on feel it. i spent of lot of my life suppressing my feelings (usually to spare others' feelings). Not healthy. i finally learned that for me the best way move on in spite of bad feelings is to identify them and feel them fully.
i've been 'Dawn Patrol' for people contemplating suicide. i've talked with family of suicidal people trying to help them understand. My first instinct is usually to try and help/uplift people--that's doesn't mean being a Pollyanna or toxically positive (yes there is such thing). It means meeting them where they are and helping them develop tools for dealing with their triggers. It means reassuring people at their most vulnerable then helping deal with their problems when their ready.
Also i've talked elsewhere about the benefits of my NDE. For one thing it made clear that while we can exit this reality, we cannot exit consciousness. As one of A. A. Milne's "Pooh" characters said 'Where ever you go, there you are'. We can leave these bodies behind but not ourselves. But it also gave me some clues to coming to terms with this individual life and becoming the enduring self/soul/consciousness i want to be.