I help admin a large Facebook group (8000+ members) for sleep paralysis that you're welcome to join:
I mostly just activate accounts. I don't spend a lot of time there myself.
There's also a small sleep paralysis group (less than 2000 people) here:
The two groups above are open to both paranormal and scientific/medical points of view on SP. Sometimes arguments break out between people who have different points of view.
Another FB group I'm a member of is Sleep Paralysis and Astral Travel. The title says it all.
There's also a group called "Sleep Paralysis and the Supernatural" but it's more Christian based. The people there believe SP is caused by demons and that belief in Jesus is the way to try to cure it.
There are two ANTI-paranormal groups: "Sleep Paralysis ISN'T Supernatural" and "Sleep Paralysis is NOT a gift!" Those groups were created by people who got kicked out of the large group because they kept ridiculing those who believed in supernatural explanations for sleep paralysis.
These are all closed groups, which means anyone can find the group and see who's in it, but only members can read posts.