The death rate in the week between Christmas, 1944, and New Year's, 1945, increased in camp beyond all previous experience. [...] the explanation for this increase did not lie in the harder working conditions out the deterioration of our food supplies or a change of weather or new epidemics. It was simply that the majority of the prisoners had lived in the naive hope that they would be home again by Christmas. As the time drew near and there was no encouraging news, the prisoners lost courage and disappointment overcame them. This has a dangerous influence on their powers of resistance and a great number of them died.
Viktor E. Frankl - Man's search for Meaning