UV turns THC in CBN, oxigen does it too, so as heat.
Some info on CBN
"CBN is also psychoactive, though much less so than THC
The presence of CBN with THC seems to reduce the feelings of anxiety that some people feel with high levels of THC
The presence of higher levels of CBN with THC can cause people to feel less "messed up" from exposure to THC
Too much CBN can make people feel groggy or sleepy
Therefore, CBN promotes uninterrupted sleep
THC turns into CBN when exposed for long periods to air or UV light
CBN levels in buds can be influenced by harvest, drying, and curing methods
Waiting longer to harvest, until trichomes have turned amber, often results in higher CBN levels
Higher exposure to air during drying/curing, and longer curing processes result in higher levels of CBN"
Robert Clark wrote about trichomes and what they tell us in his book Marijuana Botany;
The elevated resin heads appear clear, since fresh resin is still being secreted, often being produced in the cellular head of the trichome. At this time THC acid production is at a peak and CBD acid levels remain stable as the molecules are rapidly converted to THC acids, THC acid synthesis has not been active long enough for a high level of CBN acid to build up from the degradation of THC acid by light and heat."
I´ve read that fresh buds have a low CBN rate, it will increase when curing/storing.
As the plant need light to produce THC, that 48hrs of dark will stop THC production and thats not what you want.
As flowers grow they produce THC, if light and air could oxide THC that fast, we where going to have a lot of CBN even in fresh buds.
THC production in 48hrs is bigger than the oxidation caused by the light in the same period of time, and as oxigen also turns THC to CBN 48hrs of dark wont stop the oxidation but will stop THC production.
Simple math?
So, if u dont want too much CBN, just harvest before u get a lot of amber flowers, dry it, and store it properly.
Thats MY opinion.