Is it a ReptiSun T8 or T5? Another suggestion is that your tank looks quite dark. Your UVB should be 2/3 of the tank, it looks like your bulb is too short. Bearded Dragons have a "third eye" on the top of their head and this is how they seek heat and light. When it isn't bright enough and warm enough, that "eye" isn't "activated." It could be with her bask temperatures so low and her tank being dark, she isn't achieving proper UVB and heat exposure to activate everything. Since they are ectotherms, they rely on their environment, so she could be in a perpetual state of sluggishness.
And as for the night bulbs, you never want to use light bulbs at night. Dragons do not need to be heated unless temperatures drop below 65-70, and if they do, use and a ceramic heat emitter instead. CHEs produce heat and no light since they are a coil covered in ceramic, so they aren't a bulb. They also produce gradient heat instead of a direct bask spot. Providing a basking spot at night doesn't allow for night time temperatures to drop sufficiently for their bodies to cool off and recuperate. Consistently warm temperatures and lighting (even if a light is red or purple, they may not see that color but can still see the light as either white, gray, or another color) will disrupt sleep patterns, their circadian rhythm, and hormone production. It can also lead to constant dehydration, since they are always hot and their bodies can't cool down, which would add to sluggishness and in extreme cases can be fatal. The light can also be preventing her from sleeping properly at night, therefore making her lethargic during the day.
The most important thing as far as vets go is to get a fecal test done. As long as she has already been to the vet before, they will let you drop off a fecal sample without making an appointment. Even if she is brumating, you want to make sure she is parasite free before doing so.