>>Anyone else heard of this? Would this actually be helpful in any way? Would it present any risks if allowed?<<
Here's one of Dr. Rosekind's (et al.) original articles describing his research at NASA on the subject:
http://olias.arc.nasa.gov/zteam/fcp/pubs/jsr.art.html
Here's a short interview where Dr. Rosekind extolls the virtues of a short nap in the cockpit:
http://health.discovery.com/centers/...rosekind3.html