Keeping Up With the Kardashians season 12 will return with a brand new episode this Sunday and the focus will be on Kendall Jenner, the fourth daughter of Kris Jenner. In the promo of the upcoming episode released by E!, the reality star was seen having a serious discussion with her mother regarding her health.

The 21-year-old American fashion model tells her mother about her reluctance to travel much as she has been suffering from sleep paralysis. "You have a week in Paris, Milan and then London," Kris tells her daughter reminding her of the work commitments she has.

"I don't know if I'm going to be able to do that. I can't travel that much. I'm like, scared. I'm freaking out because of these f--king paralysis things. I'm scared to fall asleep because it keeps happening to me. It almost feels like my heart stops," she responds to her mother.

Kris, on the other hand, is worried for her work schedule and says: "The nature of what you do for a living and for your career is flying around the world. You have designers that have already booked you and are counting on you to show up."

"I am just telling you that my health is a bigger deal" Kendall replies to her mother.

"Kendall basically lives on an airplane. So the anxiety on an airplane and the sleep paralysis is a huge problem. Sometimes it's been so bad that she's been paralyzed from even getting on an airplane. I've had to get on a plane and fly from L.A. to London just to get her from London to New York! So it's becoming a real problem," Kris explains.

What is sleep paralysis: According to NHS UK, it is a "temporary inability to move or speak that occurs when you're waking up or falling asleep. It's not harmful and should pass in a few seconds or minutes, but can be very frightening." The website also claims that the condition affects "people of all ages and is most common in teenagers and young adults."

KUWTK season 12 airs every Sunday night on E! network.