So? Biden's not a young guy; that's no secret.
He had a cold, and he most likely took medicine for said cold, and that made him drowsy.
A while into the debate, he stopped looking and talking like he was comatose.
He answered the questions, and he answered them with statistics, facts, and achievements. That's more than anyone could say for Donald, who lied, slandered, and blustered his way through the debate.