This is the Iron Age, though, so they sleep and wake up with the sun. It is not soon after the first rays of light start hitting the walls of the house that the sounds of drums can be heard coming from downstairs. And it's definitely drums plural, even though Tintin only saw the one the music sounds like it could not have been coming from a single drum.
Horan looks to be sound asleep, but Taharqi is nowhere to be seen.