That's what I heard too, but it was explained to me this way. THC vaporizes at a lower temprature than does the CBN, so the residue in your pipe or a bunch of roaches would be richer in CBNs and therfore more medicinal. This also means that if you are selective at your vaporizer, you can vape at a lower temp for the high, save the slightly toasted remains for vaping at higher temp for the sleep, pain, and nausea help your looking for as well as medibles. Win/win.