According to the health professionals, depression is a mental disorder which needs treatment and might cause serious affects in a patient’s life. Harvard.edu says that “there are many possible causes of depression, including faulty mood regulation by the brain, genetic vulnerability, stressful life events, medications, and medical problems. It’s believed that several of these forces interact to bring on depression.” 
According to me; depression is a state of awareness. Just to be clear, these are my ideas and I don’t claim any truth in them. I’m just thinking out loud. Depression is a state of awareness I say and I add: People with depression or other “mental disorders” actually tend to have a more realistic view of the world.
Let’s compare my idea of universe with symptoms of depression. According to Helpguide.org, depression has 10 common symptoms.
Feelings of helplessness and hopelessness
The world is dying. Society is in a constant war. People are starving. We spend 20 years for education only to sell ourselves for the rest of our lives to a company just to earn money which we have no time to spend on leisure. Is it absurd that I feel hopeless?
Loss of interest in daily activities
As stated above, the world runs in a smooth system and if you are trying to block the well-oiled-machine by asking questions, you end up hopeless and this leads to a life where every daily activity feel pointless and empty.
Appetite or weight changes
Henry D. Thoreau says that we feed our inner fire with food. If you want to get warm, you eat. When you feel hopeless about life, this might effect the way you eat. Well… I dunno. I can’t really explain this symptom.
In my opinion, sleep is the closest we can get to death, without dying. Perhaps our body is trying to tell us by being excessively sleepy or reverse?
Anger or irritability
Everyone is going on with their life, getting married, having kids, graduating etc. while you are stuck hopelessly. Maybe this is the reason behind our low tolerance against people.
We are all worthless pieces of garbage. Is it not true? We are not unique. We are not delicate. I believe it is the healthy thing to do to accept that we are not one-of-a-kind.
This can mean a lot of things. One: I’m trying to enjoy life a bit. Two: I’m trying to escape reality a bit.Either way I think reality is not bearable.
What’s the point anyway? Reading a book- why? In the end life is still meaningless.
Unexplained aches and pains
I don’t have much to say about this. But depressed people tend to exercise less. That can be the reason of aches.
Loss of energy
There is a rule in physics: Energy is never lost. It’s still in you, in me. But there is nothing meaningful to use it.