I would steer your enquiry towards Heaven and Hell by Aldous Huxley.

Whilst he is better known for The Doors of Perception, Heaven And Hell considers the nature of religious epiphany, he identifies several common factors that stimulate part of the brain leading to spiritual revelations and rapture.

To oversimplify they are Refracted and flickering lighting, mild asphyxiation , fasting and sensory deprivation,ie caves and cells.

In the two examples you listed Huxley would use as two separate stimulus on the brain, Insense he catatagorized as a mild asphyxiant alongside chanting. Whereas lighting a candle would be an example of flickering lighting,something that has been believed to be a key tenet of religious rituals since Lascaux was discovered,

I am not sure Huxleys observations would stand up to rigorous historical analysis, but should give you food for thought, the essay in question is available online here

http://www.ignaciodarnaude.com/espiritualismo/Huxley,Aldous,Heaven%20and%20Hell.pdf