Kendall Jenner suffered from "very bad panic attacks"

Speaking in a preview clip ahead of her four-part series with Vogue called 'Open Minded', she said: "Two or three years ago I genuinely started having very, very bad panic attacks. I was having frights in the middle of my sleep, literally felt heart palpitations. I couldn't breathe. I was pretty bad."

Meanwhile, Kendall previously admitted she has "struggled a bit" with her mental health.

She said: "I was really, really young and I remember not being able to—feeling like I couldn't breathe and venting to my mom and being like, ‘Mom, I feel like I can't breathe. Something must be wrong.' And she of course took me to a bunch of doctors just to make sure that I was okay physically, and I was. No one ever told me that I had anxiety."Maybe three or four years ago it came back completely full-on ... I would have crazy panic attacks. I finally kind of got the information that I needed about it."

However, once Kendall knew what she was struggling with, she found new ways to cope.

She added: "On the days that I don't really have as much going on I tend to get a bit anxious and to calm myself down I'll usually read a book or meditate ...

"For me, I have good days and I have some really anxious days, so I'm really off and on ... It is important, now more than ever, that we come together to promote acceptance and inspire hope."