The Australian actor, 54, portrayed the tormented author who was struggling with her own mental health while trying to write her novel Mrs Dalloway in the 2002 film.
Kidman won the best actress Oscar in 2003 for the character but admitted she probably does not "consider danger enough" when taking on such roles.
Speaking to This Cultural Life on BBC Radio 4 in the UK about creating the scene in which Woolf drowns herself in a river.
"I don't know if I ever thought of the danger, I think I was so in her," she said.
"I mean, I put the rocks in my pocket and walked into the river. Over and over again. I probably don't consider danger enough.
"And I think I was in a place myself at that time that was removed, depressed, not in my own body.
"So the idea of Virginia coming through me, I was pretty much an open vessel for it to happen.
"And I think Stephen (Daldry, the film's director) was very delicate with me because he knew that."
The actress did not wish to elaborate on why she felt this way but noted that "depression hits you at different times".
"I was open to understand it, which I think is probably the beauty of life as an actor," she said.
"There's a point where you're like, oh, I have so many experiences now.
"I've delved and traversed many different landscapes of mental health and loss and ideas and joy and raised birth and you know, life is what it is.
"It's far more examined for me now than when I was 14.
"I'm definitely in it. I'm definitely feeling it and definitely aware of the preciousness of it and the time. The other extraordinary thing I'm very aware of is I'm around and exposed to some of the greatest minds in the world.
"I'm the recipient of their focus. I'm grown by them, I'm taught by them, I'm shaped by them, and I'm seen by them, and that is, that is a beautiful, beautiful journey to be on.
"I hope it still continues, but I value it. I don't take any of that for granted and I know what it is. I try to stay in that place. I definitely don't want to shut down as I get older. I want to become rawer, and more open, more available and freer."
Kidman has also received Oscar nominations for her roles in 2001's Moulin Rouge, 2010's Rabbit Hole and 2017's Lion.
She is currently starring and helping to produce the upcoming female-led TV series Roar, which is based on Cecelia Ahern's collection of 30 short stories published in 2018.
She has also taken to the stage during her career, including the West End production of Photograph 51 which premiered in 2015.
Kidman said she would "love to be brave enough" to return to theatre and teased that she may have a show on the horizon.
"There's something I'm circling with a director who's a film director, but he's also got a lot of theatre experience," she said.
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