I think some beardies can get stressed if they don't have any stimulation. I've noticed that my beardie seem happiest perched on a windowsill staring outside for hours on end. She loves basking in the sun and takes an active interest in watching cars and people go by. Her behavior makes it undeniable that she likes staring outside. Sometimes she will run back and forth in her tank, asking to be let out. As soon as I plop her in the windowsill, she's happy as can be and only climbs down when a bird startles her or if she has to poop or something.
If your beardie seems depressed or lethargic, see if you can move his tank within view of an open window so he can get some visual stimulation. Just make sure that direct sunlight doesn't shine onto the tank, as you can cook your dragon. Also be aware that beardies don't like birds, and make sure he has a place to hide if he sees a bird.
If this isn't possible, perhaps you can try to arrange some sort of safe window viewing perch that you can use to give your beardie supervised window access. My couch rests against a windowsill and I stacked several large books across the back of the couch and windowsill and covered the books with a towel. That way she has a large area to lay on (and can't fall) and she knows that if she gets spooked by a bird, she can run down the couch, hop to the ground, and hide under the couch. She does this all the time. When I have her out, she climbs up and down the couch to her basking area to suit her mood. She loves it.