Part of the problem with most other studies are that it is very had to metricize on-the-job performance and sleepiness. Some of the cool things about this study are:
1) very clear metrics to measure performance (reaction time)
2) very consistent testing (repeated trials over an actual 9 hour flight, then over 4 days of additional flights)
3) additional non-subjective metrics for sleepiness (the teams strapped an EEG on the pilots while they were flying to monitor brain activity!!!)
It's frustrating, but most health and wellness magazines are a bit like an echo chamber with no clear references to source data.
There are two ways to nap: a quick 20 min nap doesn't take you into deep sleep (characterized by delta wave patterns--google SWS) and let's you wake with much less sleep inertia. It's refreshes, but doesn't consolidate memory. A longer nap (60-90 min) typically takes you into deep sleep, and is harder to wake from. However, a long nap will give you memory consolidation and recovery on par with a full nights sleep.
It's frustrating, but most health and wellness magazines are a bit like an echo chamber with no clear references to source data.