Emma Watson Talks 'Controlled Substances' on Letterman (watch!) 1Emma Watson seemed to know remarkably little about the personal life of her Harry Potter co-star Daniel Radcliffe, despite spending 10 years filming the series together. Daniel had a drinking problem? Who knew?

The elfin Radcliffe touched off a media storm when he revealed in an interview with GQ magazine that he developed a drinking problem while filming the hugely successful movies to deal with all the pressure.

But Watson told David Letterman she didn’t really have a clue.

“To be honest, it’s really not something that I genuinely know much about,” she told the crusty talk show host.

“But as far as I know, he never took a sick day. He was like the most professional, amazing guy ever,” she said.

Dave talked about the pressures of show business, declaring that we are “all like monkeys on a rock,” and invariably asked the squeaky clean Watson if she used “controlled substances.”

Emma did her best to dodge the question.

“I mean, yes, I have tried spirits! Of course, I’ve tried spirits,’ she confessed.

‘I mean err, there are substances, whiskey… I’m dying here,’ she laughed nervously.

Watson, however, did point out that she’s legal to drink. You have to be 18 in the UK. “But I’m actually legal to drink now in the US. It’s worth mentioning, I’m 21!” she said.

Dave pressed on, and Emma finally made the big reveal:

“Yes I have been drunk once in my life, as everyone does. I’ve got drunk, I’ve been drunk and I’ll bow to that.”