Have a read of this study posted mid last year, https://www.karger.com/Article/FullText/489030
"Cannabis growers have been interested in UV light for a long time; however, the relationship between cannabinoids and UV-B is not as direct as first proposed. Increased concentrations of THC, but not of other cannabinoids, were found with UV-B treatment in both leaf and floral tissues of drug-type plants [20, 25]. In contrast, none of the cannabinoids in fiber-type plants were affected by UV-B radiation. In a more recent study, hemp leaves were exposed to UV-C radiation and analyzed for changes in secondary metabolite biosynthesis [26]. While no remarkable change in the cannabinoid content was observed, significant increases in dehydrostilbenes and cinnamic acid amide derivatives were found."
