It has of course been proven that THC will cause anxiety but CBN causes confusion and disorientation and in someone who has anxiety problems, that can set off their anxiety big time.
Anxiety is normally associated with fast speedy sativas but I have known people who would totally freak after smoking a heavy indica that should have left them very relaxed. They always waited for a fair to large percentage of amber trichomes, and amber is a sign of degraded THC, THC that has oxidized and become CBN. They started harvesting earlier, at the very first sign of amber showing up, and they stopped suffering from anxiety from their heavy indicas they picked for calming relaxing affects, but caused the opposite when grown until there was much to a lot of amber.