Lots of people are unaware of the intense studies that have been performed concerning Marijuana growth.
The subject of this thread has been studied and strong evidence found that light deprivation prior to harvest negatively affects the THC levels and resin production.
From: "Marijuana Botany <An Advanced Study: The Propagation and Breeding of Distinctive Cannabis>
by Robert Connell Clarke
Factors Influencing THC Production
Many factors influence the production of THC. In
general, the older a plant, the greater its potential to pro-
duce THC. This is true, however, only if the plant remains
healthy and vigorous, THC production requires the proper
quantity and quality of light. It seems that none of the bio-
synthetic processes operate efficiently when low light con-
ditions prevent proper photosynthesis. Research has shown
(Valle et al. 1978) that twice as much THC is produced
under a 12-hour photoperiod than under a 10-hour photo-
period.
****
End Quote
The elimination of light during the end plant life causes an increased rate of death to the plant. It doesn't increase THC production or resin production. Actually, it DECREASES THC production and resin production. In fact, total loss of light will result in the elimination of THC production. The THC production will slow during the first 24 hours and come to a complete stop in the second or third day. If the lights were left on, THC production would have continued.
I would strongly advise anyone who is seriously interested in growing world class weed to purchase this book.
It will educate you in the REAL characteristics of Marijuana and help you to understand why many of the myths involving it's growth are fiction, not fact.
To sum up, NO, light deprivation will not help your plants to increase THC or resin. Leave your lights on at a 12/12 schedule until you chop your plants. To do otherwise will decrease it's potency. If you even decrease your light to a 10/14 on/off cycle, you'll be decreasing the potency of your plants drastically as compared to what they would have been on a 12/12 schedule.