Like I said to my therapist a couple days ago
(she said it had been one of the better explanations shes heard)
"Living with PTSD is like struggling through an entire day, flying emotions, THEN we have to try and fall asleep, basically impossible when you are feeling anxious, then after a terrible sleep... you wake up to have to do the whole damn battle again."

From my personal experience, I have chosen to only tell select few people about the fact that I have PTSD. My supposedly best friend told me to basically "get over it" and just stop being depressed.

And the fact that we not only have a hard time understand what is going on in our own head... let alone explain it to people around you... well, I honestly don't think that someone without PTSD to fully understand what we are actually going through.

I think one of the best analogys is the one about the "PTSD cup"