B1A4's Jinyoung revealed he and Sandeul suffered a sleep paralysis episode at the same time.

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On the September 16 installment of 'Knowing Brothers', Jinyoung asked, "What did Sandeul and I suffer 5 times constantly in a music show waiting room?" After a lot of wrong guesses by the 'Knowing Brothers' cast members, he finally said, "We experienced sleep paralysis."

Jinyoung added, "Sandeul saw that I was suffering, so he woke me up. Just like that, Sandeul and I suffered sleep paralysis 5 times. The last time, I opened my eyes a little and saw that a ghost was holding up a big mirror and reflecting me in it. It wanted to show me how much I was suffering."

Sandeul then commented, "I was shocked at the time, so now I always refer to it with respect as Sir Ghost."