In a preview clip of Sunday's upcoming Keeping Up With the Kardashians, Kim admitted she had never heard of the ailment before.
The 21-year-old looked gorgeous but exhausted as she attempted to explain to her older sister, 36, what she's been going through and how it's been 'getting to her.'
Sleep deprived: Kendall Jenner looked exhausted as she attempted to explain her ailment to sister Kim Kardashian on the preview of the show airing this Sunday
'It's like you're asleep, and then in the middle of the night...basically, your mind wakes up but your body is still asleep,' Jenner divulged, wearing a black satin bralet and choker with full hair and makeup.
'You wake up, and nothing can move.'
The Vogue cover girl added: 'It's the scariest thing in the entire world, you're freaking out because all you want to do is be able to move, so you're laying there, trying to move, trying to relax,' the model expressed excitedly.
Awestruck: Kendall's older sister was shocked and confused about the mysterious sleep problem
Awestruck, her Mrs Kanye West probed for more.
'And you can't communicate it?' Kim asked, her mouth agape in shock.
In a confessional clip, the Selfish author reacted further, saying she 'feels so bad' for her little sister and that she's 'sorry that she's been going through this.'
Scary nights: 'It's like you're asleep, and then in the middle of the night...basically, your mind wakes up but your body is still asleep,' Jenner divulged on the preview of Sunday's show
Not so selfish: In a confessional clip, the Selfish author reacted further, saying she 'feels so bad' for her little sister and that she's 'sorry that she's been going through this'
'I thought I was having anxiety, this is like, so much scarier,' the mother-of-two confessed, 'I've never heard of sleep paralysis and I think it sounds like such a crazy experience.'
Meanwhile, the Kardashian-Jenners have had a lot of celebrating to do this week.
Silver surfer: Kendall Jenner dazzles in a $9,000 dress that emulated Paris Hilton's 21st birthday dress
Thursday marked Kendall's 21st birthday and Friday was Kris Jenner's 61st.
The family hosted Kendall's birthday dinner at celebrity hot spot Catch in West Hollywood and returned just a couple nights later to celebrate the momager.
Keeping Up With the Kardashians airs Sundays on E!
All white:The 'momager' dazzled in a bright white co-ord as she headed home from the swanky dinner party at Catch in West Hollywood with her boyfriend Corey Gamble, 35