Even thought this is an "Off topic" topic, I'm not quite sure it will end up over there.
We shouldn't necessarily believe everything we read or hear, unless that information comes from a reptile (and/or bearded dragon) expert/vet. I believe the members, especially those seasoned members, on this site strive to provide the best husbandry possible for their bearded dragons, and it is for that reason that I seek their advice.
Now, that said, I've surfaced two articles from two reputable and peer-reviewed publications. I'd like to elaborate and provide documented resources as a response to some of the comments made during this thread.
The first is "Two Common Disorders of Captive Bearded Dragons (Pogona Vitticeps): Nutritional Secondary Hyperparathyroidism and Constipation" by Kevin Wright, DVM. Published in Journal of Exotic Pet Medicine, vol. 17, no.4, October 2008, pages 267-272.
The article does not specify the recommended time lights should be left on and off. However, he does point out constipation (caused by dehydration) as one of the most common ailments in pet bearded dragons. He does not mention basking lights as a cause of dehydration, or to limit basking time. Instead, he points out that constipation/dehydration is cause by insufficient water intake (obviously) through other husbandry practices. Providing vegetation to eat, spray-misting the dragon or side of the tank, and lukewarm baths are recommended to improve hydration.
The Second article is "Husbandry and Veterinary Aspects of the Bearded Dragon in Australia" by Michael James Cannon, BVSc, MACVSc. Published in Avian and Exotic Pet Medicine, vol. 12, no.4, October 2003: pages 205-214.
This article stresses the importance of different Pogona species and their separate environment adaptations and needs. It states that bearded dragons will assume different positions in relation to the light/heat source to regulate their body temperatures. They will lay parallel to the rays to soak heat, and will stand perpendicular to the light to minimize heat intake. They may also seek shade to reduce heat intake. "For the average bearded dragons the [preferred body temperature] PBT is 35 [degrees Celsius]." Cannon suggests that the range of temperatures provided for the dragons range from 35 to 40 degrees Celsius. He also suggests to provide that heat through a single light/heat source at one end of the cage.
Now, all
that being said (feel free to roll your eyes :roll
, I believe most of the bearded dragon owners on this site attempt to provide conditions and environment which most closely replicates their natural environment, eliminating proponents of that natural environment which may cause harm to their dragons. For many if not most of the owners on this site, that means leaving basking lights on for regular day/night intervals to simulate a regular day/night cycle. We really don't know the full practices of bloodbankdragons, and if we want to know how they came to that conclusion and their sources, we should ask them directly instead of either taking it as true, or presupposing the reasons as to why.
The main concerns of bloodbankdragons's practices to those who responded to this thread are if they are providing sufficient UVB/UVA exposure, and if they are keeping the tanks warm enough (35-40 celsius) during the day.
:!: WARNING: MY OPINION AND EDUCATED GUESS MAY FOLLOW :!: It seems to me that heat and dehydration go hand in hand. If the breeder is only leaving lights on for 6 hours a day, they must be heating the tank in an alternative manner. If the tank is still being heated to the optimum temperatures, then the dragons will continue to become dehydrated, regardless of whether the light is on or not.