No nightmare could be as horrible as the reality of the concentration camp.
Book: Man's Search for Meaning
Man's Search for Meaning is a book by Viktor Frankl, a psychiatrist and holocaust survivor, describing his experience in the Nazi concentration camp and his psychotherapeutic method: logotherapy.
When first reading this book, I was struck so heavily by the following narrative:
"I shall never forget how I was roused one night by the groans of a fellow prisoner, who threw himself about in his sleep, obviously having a horrible nightmare. Since I had always been especially sorry for people who suffered from fearful dreams or deliria, I wanted to wake the poor man. Suddenly I drew back the hand which was ready to shake him, frightened at the thing I was about to do. At that moment I became intensely conscious of the fact that no dream, no matter how horrible, could be as bad as the reality of the camp which surrounded us, and to which I was about to recall him."