What is Depression?

I want to make it perfectly clear that depression is a mental illness. There is a difference between the sorrow that comes from sin and clinical depression. The kind of depression I am talking about here is the depression that seems to come for no reason, although it may be triggered by some event or change. It does not start because of something we do wrong and it won’t go away by repenting and seeking forgiveness. The bishop cannot cure it, although he may be able to point sufferers in the right direction or recommend professional help.
There are a few different types of depression. For my purposes, I obviously refer mainly to my own experience with clinical or chemical depression. The exact cause of depression is unknown, but it is known that depression involves an imbalance of chemicals in the brain. According to the Diagnostic and Statistical Manual of Mental Disorders, what I have suffered from would be termed Major Depressive Disorder. This involves Major and Minor Depressive Episodes, which are periods of two or more weeks at a time in which depressive symptoms are present. Another disorder, called Dysthymic Disorder, involves depression for two or more years straight, rather than distinct episodes.
A Minor Depressive Episode involves two to five of the following symptoms, and a Major Depressive Episode involves five or more:
1. depressed mood most of the day, nearly every day
2. diminished pleasure in activities
3. significant weight loss or gain
4. insomnia or hypersomnia
5. psychomotor agitation or retardation
6. fatigue or loss of energy
7. feelings of worthlessness or excessive feelings of guilt
8. difficulty concentrating
9. recurrent thoughts of death; imagining, planning, or attempting suicide.[1]
Any person with this last symptom should seek help immediately, whether or not they have any more symptoms.
This information is not meant for self-diagnosing, nor should it be used to replace seeking help or advice from someone more qualified to give it. It is simply a guide for anyone who believes they may have depression, or for anyone who wonders what depression entails. This information comes from the manual used by mental health professionals to diagnose mental disorders.
Before continuing to read, please know that I have described depression in some detail in this book, feeling that it needs to be said. Some people will find it helpful to read, to feel that someone understands what they are going through. But for others, it is simply a reminder of terrible emotions and can heighten sensitivity to them, making it more difficult to bear. If you are depressed, please skip anything that does not help you. The majority of this book is full of hope and lessons learned, and is meant to uplift and inspire. There are lessons to be learned from depression, as from any experience in life. I would like to share some of my own lessons that I have learned from the difficult school of depression.
[1] DSM-IV, 356.