Well, John Lydon did demonstrate a marked increase in psychoactive cannabinoid content in plants exposed to UVB back in the 80s.

I still have a copy of the abstract of the redo of the study in 2008 - UV-B RADIATION EFFECTS ON PHOTOSYNTHESIS, GROWTH and CANNABINOID PRODUCTION OF TWO Cannabis sativa CHEMOTYPES - Lydon - 2008 - Photochemistry and Photobiology - Wiley Online Library

I figured the UVB exposure from the beginning would've produced the best results, as the plant has had more time to realize that this is going to be the typical exposure it's going to get, and as such, it needed to produce more protection for the calyxes (and the possible seeds within) by gettling larger and producing more trichomes, and more fan leaves.

Want pics, but good comparison.