Some years ago I had this notion to test Frankincense. It was at Christmas time, and I just wondered if there may be something to it, some reason for including it so prominently in the pageants, and mostly after learning how the biblical kingdom known for producing the resin had never once been at war with anyone. In part I wondered if the strong and distinctive scent might become Pavlovianly linked to the Christmas season, but I also wondered if maybe the conditioning was also the other way around. I wondered if the psychotropic qualities of their chief export might have had an impact on their treaty negotiations.
In the science results today, it seems I was not the only one asking such questions:

burning frankincense (resin from the Boswellia plant) activates poorly understood ion channels in the brain to alleviate anxiety or depression.

"In spite of information stemming from ancient texts, constituents of Bosweilla had not been investigated for psychoactivity, ... We found that incensole acetate lowers anxiety and causes antidepressive-like behavior. Apparently, most present day worshipers assume that incense burning has only a symbolic meaning."
[ Incense is psychoactive ]

"... ion channels in the brain ..." -- I hope that sinks in for those who may have scoffed at aromatherapy, have them wake up and smell the coffee so to speak, and a lesson learned for all those who diss clearly empirical experiences because they believe there is no scientific explanation for it, because today's Science was always yesterday's Occult :) Back at the Frankincense, the jar I bought off eBay for $4 still has plenty left in it, enough for many more Christmas seasons; we use an aromatic oils warmer to melt it, and it takes only a tiny lump to fill the house with its special holiday cheer.