Sleep paralysis is rooted in problems with REM sleep, reports NPR.

Josh Smith says it all started when he was five years old. He’d go to sleep and in the middle of the night, he’d wake up, his body rigid.

One night stood out to him in particular: He was 16. He’d just had sex with his girlfriend and it was stressing him out. Raised Evangelical, he wondered if he was going to hell for premarital sex.

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