Scientifically it's true.. Whether or not your eyes or body notices a difference is a different story. There are several ways to stress a plant before harvest. This is one of them. But the science behind it is true. When the plants are in darkness for the last 48 hrs, it tricks the plant into believing the season's are changing and that it is at the end of life. The plant increases resin production as a last ditch effort in hopes that it increases the chances of pollen sticking to the pistils and pollinating the plant. Is the increase noticeable to the human eye? Probably not.. But that is the science behind the concept.