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.
In the study, NASA teams first picked out a group of commercial airline flight pilots flying a standard itinerary between Hawaii, Japan and Los Angeles. They then divided the pilots into two groups: A Rest Group (RG) that was allowed a 40 min cock-pit nap during the cruise portion of each flight and a No Rest Group (NRG) that was not allowed a mid-flight nap. Over the course of a six day study, the pilots flew four (4) flights during which NASA teams analyzed them for wakefulness before, during and after their flights. The teams even brought along EEG and EOG machines to measure the pilots’ brain activity during the tests to confirm whether or not the pilots sleeping, and how alert they were.
For the rest of the story: http://priceonomics.com/the-nasa-studies-on-napping/