In general, scratching at the glass usually means that they either want something outside the enclosure, or else want to get away from something that's inside the enclosure. Does he have the tank to himself or are there any other critters in there with him?
Otherwise, given that he's an adult male and given that it's almost spring (assuming you're in the northern hemisphere), he could just be going hormonal. Have you noticed any
black bearding or head bobbing? Are there any female beardies around? He may just be trying to get out so he can find himself a lady friend and make little dragons.
If that's all it is, then you may be able to hold on to what's left of your sanity be realizing that the craziness won't last forever, although I'm not sure how long is typical...
:?: If anyone else has male beardies that go nuts in the spring or at whatever time of year their biological clock is set for (mine did it right around the winter solstice once :roll: ), what's your experience? --how long does it usually go on before they get back to whatever is "normal" for them?