People like me, we learn to do 8 to 5, more or less, or 6am to 6pm, or whatever is needed. We mostly seem normal. I am a bit rigid but I have a good sense of humor (on most accounts).
But it is EXHAUSTING acting normal. Once I done playing my role, I want to numb all that tension and grief into oblivion. The day is act 1. The night is act 2, and this can be repeated across s lifetime.
“He was so quiet”, we hear of the latest mass murderer, or guy who had someone locked in a closet, or whatever. Two lives. Two segmented lives. Act 1 and Act 2, the second hidden.
Often soldiers are like this. Keep them in a container of duty and they function fine. When leave the service though, they may just want to buy a shipping container and 40 acres in back of the back 40, and hide from the world. Some of our best soldiers do this, I am told, by someone in a position to know. The long term accumulation of fear, based on first hand knowledge of what is possible, just adds up and sinks them. Maybe they are happy, but I think happier is the better word, relative to all other options.