Thanks for the added info. I do prefer UVB lighting to be housed inside the enclosure. Their effectiveness is directly tied to their distance from the surface. For example with compact fluorescent (CFL) UVB bulbs, a 10.0 bulb should be placed 16-18" and a 15.0 bulb should be placed 20-22", but no more, from the surface. For larger b, mercury vapor bulbs provide three feet of UVB penetration.
I am copying my bearded dragon husbandry sheet for your reference, it has recommendations on diet, temp, UVB lighting, supplementation, etc.
Bearded dragons are lizards that are native to Australia. With good care they can live 10 years or more and make excellent pets. It is typically recommended to house them singly, though sometimes it is possible to keep breeding pairs together. It is recommended that the enclosure be at least 10-20 gallons for juveniles and 75 gallons for adults. Care should be taken as to the enclosure substrate as they may potentially ingest loose substrates. If you do use something like paper pulp substrate, feed the dragon in a separate enclosure to prevent substrate ingestion. Paper towels or newspaper are good substrates that are easy to replace very 1-2 days to prevent waste accumulation. It is fine to include cage furniture in the enclosure such as large rocks, pieces of driftwood or cork bark. Hiding boxes or areas are required if you have more than one dragon housed together.
-Temperature: Temperature is very important for keeping your dragon healthy with a gradient of temperature from cool or warm. Daytime temperature range with a cool side at 77-80F (25-27C), a warm side at 85-90 (30-32C) and a very warm, focal basking area of 95-105F (35-41C) for adults and juveniles and a slightly warmer 95-110F (35-44C) for babies. A nighttime temperature range of 70-75F (21.5-24C) should be provided. 30-40% humidity is recommended. Although they are from an arid region, having sufficient humidity is important to respiratory and skin issues and not too much humidity is important to prevent secondary infections from moisture loving microbes.
-Lighting: In addition to tank lighting that supplies UVA and visible light exposure, bearded dragons require UVB exposure to maintain proper health. Just as with temperature, their enclosure should have a gradient of UVB exposure with no UVB at the coolest end and highest at the basking spot. To avoid over supplementing, at least ¼ of the tank should not be directly illuminated with UVB light. Distance from the UVB bulb is vital as it dictates how much UVB exposure an animal will receive in the basking site. Distance depends upon the type and UVB output of the bulb. The most common types of UVB bulbs used with bearded dragons are the compact fluorescent (CFL), linear fluorescent or mercury vapor bulbs. For example, a CFL or linear fluorescent 10.0 bulb should be placed no more than 16-18" from the basking site while a 5.0 bulb should be placed 12” or less. A mercury vapor bulb can be used in a larger enclosure due to its greater depth of UVB penetration, up to 3 feet. The mercury vapor bulb’s wattage dictates the heat output of these dual use bulbs it does not change the UV penetration. There should be no glass or acrylic between the bulb and the surface as these will block UV light. Note that metal screening between the bulb and the enclosure will cut UVB output of the bulb significantly, sometimes as much as in half. Conversely, UVB light reflectors can improve UVB penetration by bouncing and focusing the UV light produced by the bulb. All UVB bulbs loose effectiveness over time, even if the light still appears to be working, it may no longer be producing UVB. It's recommended that you change the bulbs regularly, compact fluorescent bulbs at least every 6 months, linear fluorescent bulbs and mercury vapor bulbs every 12 months. Some bulbs may last longer but the only way to know for sure if they are still effective is to measure their UV output with a meter that measures UV Index or total UVB.
-Diet: Balanced diet of 30% vegetables and 70% insects for a young, bearded dragon (< 6 months old) which are more carnivorous than the omnivorous adults. That should be reversed as they age and adults fed 70-80% of their diet as vegetables for an adult. Greens should be introduced to bearded dragons at a young age. Nutritional insects include black soldier fly larvae (soldier worm larvae), superworms, earthworms, Dubia and cockroaches and the occasional wax worm, mealworm or silkworms (limit them due to their high fat content). Vegetables should be a variety of primarily dark leafy greens (dandelion greens, parsley, cilantro, watercress, escarole, endive, chicory, etc.). Some greens have high amounts of goiterogens which can impact thyroid function so while they can be fed and are nutritious, feed them in moderation and in rotation with other vegetables. Examples include, bok choy, broccoli, cabbage, kale, mustard/collard/turnip greens, arugula, cauliflower, and brussel sprouts. Lettuce, such as romaine, iceberg, green/red leaf, Boston, etc. are not very nutrient rich so should be avoided or fed in very limited quantities. Also avoid feeding oxalate ***** *****s like swiss chard, spinach or beet greens as these can interfere with calcium absorption. A small amount of other vegetables (carrots, beans, peas, squash, green beans, bell peppers, etc.) and be added; variety is the key! Salad should be chopped and offered in a clean bowl or plate once to twice a day. They can be given flowers and fruit as treats or as top dressing on the salad, with fruit not making up more than 10-20% of plant material fed each day.
-Calcium and vitamin supplementation: 3x per week dusting of salad mix with calcium powder (without Vit D3) and 2x per week light dusting of reptile multivitamin powder that has calcium, vitamin D3 and vitamin A. Insects should be dusted with calcium powder just before feeding at every meal and crickets should be both gut-loaded and calcium dusted always. Do not use calcium with vitamin D3 for daily dusting as over supplementation of vitamin D3 can lead to toxicity. It is better if the reptiles make most of their own vitamin D3 from proper UVB exposure. And if the bearded dragon is not yet reliably eating salad, in addition to daily dusting with calcium powder, dust the insects 2-3 times weekly with a reptile multivitamin powder that contains calcium, vitamin D3 and vitamin A.
-Clean environment. Avoid sand or gravel substrates as bearded dragons may eat this and become impacted. Paper towels, newspaper, slate, tile or reptile carpeting are safe alternatives. Make sure to clean the substrate at least every other day or more frequently as it becomes soiled.
If you have any specific questions about housing or nutrition, please let me know I would be happy to advise.
So I would recommend increasing his basking site tank temperature and trying to decrease humidity. If slower metabolism is the cause of the appetite and defecation slow-down then this should hopefully resolve the issue in a day or so.
However there are a number of reasons why a juvenile bearded dragon may be less energetic than normal, some transient and normal, others due to underlying disease.