It can be extremely difficult trying to describe depression and therefore make the experience meaningful to loved ones, colleagues, etc. As it happens there is a TED talk by Andrew Solomon entitled, “Depression, The Secret We Share,” that is an excellent discussion and description of depression.
In addition to the video itself, there’s a fascinating website that has quotes from the talk along with short video clips.
http://carsforhope.com.au/2014/01/the-secret-we-share/
This is a summary of the talk that fails to capture its eloquence,
“The opposite of depression is not happiness, but vitality, and it was vitality that seemed to seep away from me in that moment.” Andrew Solomon takes you to the darkest corners of his mind during the years he battled depression. That led him to an eye-opening journey across the world to interview others with depression — only to discover that, to his surprise, the more he talked, the more people wanted to tell their own stories.
http://go.ted.com/VNs