With all the dangers attending any protracted, unplanned stay in Antarctica, keeping your head can be one of the biggest challenges of all. According to Survival in Antarctica, "Survival records have shown that two things are of paramount importance to survival: the determination to live (a positive mental attitude), and the alleviation of fear." In the perpetual darkness of the Antarctic night, both can be devilishly difficult to achieve, much less maintain, and a number of scientists who have overwintered in Antarctica have suffered mental problems.