"To be honest, [Daniel's alcohol struggles are] really not something that I genuinely know much about," she told David Letterman on Monday.
"But as far as I know, he never took a sick day. He was like the most professional, amazing guy ever."
She insisted she has a very different attitude when it comes to "controlled substances."
"I mean, yes, I have tried spirits! Of course, I've tried spirits," she said. "We drink at 18 in the UK - but I'm actually legal to drink now in the US. It's worth mentioning - I'm 21!"
She confessed she got "very, very drunk once in my life, as everyone has.
"I have been drunk, and I'll bow to that!" she said, bowing to the crowd.