Answer:
compare and contrast.
Explanation:
The passage starts with a statement backed by popular opinion, "Most people think of sleep as a time when the mind and body can rest after a day of activity." After this it throws a curve ball giving a statement backed by fact, saying, "doctors know much more than that." The passage proceeds to explain what doctors know, which is comparing and contrasting, popular belief and fact.
This is pretty much the whole structure of this informational passage.