It's popular these days to make the claim that napping is good for you. This author has even built an entire startup on the premise that we should nap more and better. But what data is this conclusion based on? One important study by NASA for the most part.
In the 1980s and 1990s, NASA and the FAA were studying whether or not in-cockpit napping could improve the job performance and safety of pilots flying long haul routes. The results are somewhat technical, but almost all contemporary news articles citing a measurable increase in on-job performance due to napping are actually based on this data.