What Happens to Body Temperature and Logical Reasoning Over the Course

What happens to body temperature and logical reasoning over the course of an experiment in which volunteers go without sleep for 3 days?

A) They both progressively decline at a steady rate over the three days and nights.
B) Both reach a low level after the first sleepless night and stay at that level until the person sleeps again.
C) They become lower over days, but they improve a bit each morning compared to the previous night.
D) They become lower for the first two days and then start to improve.