"Game of Thrones" actress Emilia Clarke has revealed she suffered two life-threatening aneurysms and has undergone two brain surgeries since the show started filming.

An unknown actress before landing the role, Clarke had just finished filming her first season as Daenerys Targaryen, the "Mother of Dragons", on the HBO fantasy series when she had the first aneurysm in 2011 at age 24 while working out at a London gym, ABC says.

"Just when all my childhood dreams seemed to have come true, I nearly lost my mind and then my life," Clarke wrote in a first-person story in The New Yorker.

"I've never told this story publicly, but now it's time."

Clarke said she had been healthy all her life, but was suffering from serious stress when the artery burst in her brain.

Much of it came from constant press questions about the nudity of her character, a conquering queen, in the show's first episode.

"I always got the same question [that was] some variation of: 'You play such a strong woman, and yet you take off your clothes. Why?'," Clarke wrote.

"In my head, I'd respond: 'How many men do I need to kill to prove myself?'."

She said she suffered a subarachnoid haemorrhage the first time around, which is often fatal.

She was unable to speak her full name even weeks later.

The second aneurysm, which prompted an invasive surgery that involved opening her skull, came after Clarke finished shooting the third season of the show, which has since been green-lit for a prequel by HBO.