The challenge with PTSD is the stress of "unpredictables", that is what stresses people the most. Even sleeping can be a problem in that sleeping at night can mean perhaps having bad dreams and for some reason it feels more comfortable sleeping during the day. Some people prefer being up at night because night can bring more sense of freedom. Some people can't wait until night because it means less stress, permission to relax.

As far as struggling to deal with death? That has most definitely been a challenge to human beings going all the way back. Human beings have always thrived better when they have developed ways to have predictibility in their lives. Experiencing trauma upsets our sense of daily predictiblity and our sense of safety and sense of personal control over our environments.