Answer:
Wiesel could not sleep after their arrival to Auschwitz camp because he was not able to forget the faces of those dead children flamed and burned to ashes.
Step-by-step explanation:
'Night' is a memoir of Elie Wiesel in which he share his memory from the Concentration camp. In Section 3 of the book, he shares his memory from Auschwitz concentration camp. On the first day of their arrival in the camp, while standing in the line, Ellie saw lorry coming and loaded with heaps of bodies of dead children which were being flamed into fire.
That night Ellie couldn't sleep because the faces of those children kept coming to his mind. And that was the day when Ellie lost his faith on God.