Why did Elie Wiesel call his autobiography Night?

The choice of La Nuit (Night) as the title of Elie Wiesel's documentary-style novel is fitting because it captures both physical darkness and the darkness of the soul. Because young Elie and his father observe the sacrifice of a truckload of children in a fiery ditch and watch the flaming corpses light up the night sky at Birkenau, the darkness evokes multiple responses. The crisply methodical work of the Nazi death camps spreads over night and day and brings to life the fanatical intent of Hitler to wipe out all traces of European Jewry. The night that envelops their humanity erases mercy and human feeling.
Even more significant is the darkening of young Elie's idealism. Once moved to identify with past martyrs of the Babylonian Captivity and the Spanish Inquisition, he finds himself standing in a dismal scene that his eyes absorb in disbelief. He refrains from wondering if the smoky wreath over Auschwitz's crematories contains the ashes of his mother and sisters. By depersonalizing the fears that lurk in his subconscious and that overwhelm the badly shaken Chlomo, Elie concentrates on food, warmth, and rest. The instinctive need to pray falters on his mind's surface, yet, deep within, he continues to fight the onset of spiritual night that threatens to obliterate God from his being.