Reese Witherspoon has spoken out about her experiences undergoing hypnosis to help deal with her panic attacks from the filming of her 2014 film Wild.

Speaking to Interview Magazine, the actress – who won an Academy Award for her portrayal of Cheryl Strayed in the biographical film – said it was the film role that “changed [her] the most” due to the heavy subject matter.

Based on the 2012 memoir by Strayed of the same name, the story followed the author’s 1,100 mile solo trek around the Pacific Crest Trail following a series of intense struggles.

“I had hypnosis, I was so scared. I was having panic attacks for three weeks before I started,” she said.

Witherspoon cited the story’s “nudity, sexuality, and drug-use aspect” as some of the stressors on the project, as well as “being alone on camera with no other actors,” adding: “I hadn’t ever been alone in scenes for days and days. There were probably 25 days of the shoot where I had no other actor opposite me.

“It was just me and a camera and a backpack. I was like, “Is this going to be so boring?”‘ she recalled.”

Despite the difficulties, the actress said Wild remained “so beautiful and sacred to me, because it spoke to me so deeply about how we as women have to save ourselves”.

The film was also nominated for a Golden Globe in 2015, with Witherspoon taking Strayed along to the awards ceremony as her date that year.

In a four-star review of Wild, NME wrote: “Following a succession of fluffy performances in rom-coms such as 2010’s How Do You Know and 2012’s This Means War, Wild represents Witherspoon’s most impressive role since 2005’s Oscar-winning turn as June Carter Cash in Walk The Line.”