Originally Posted by JohnBurke

A sleep cycle of 3-4 hours is required to achieve any measurable value in rest. Despite anecdotal outdated thoughts to the contrary, cat naps don't help, and may actually impair an operator more. He or she might "feel" refreshed, but that does not equate to a tangible, scientific benefit, and the production of chemicals in the system during that time may be detrimental to safety rather than enhance it.