There are gangs of roving spirits of whom other spirits are intensely afraid. They attach themselves to the lower part of the back and cause pain by a rapid, audible, back-and-forth motion that no one is able to block. It is a pressing, squeezing motion, which they channel upward into the point of a conical shape. Any who are sent inside the cone, especially those near the tip, are wretchedly ripped apart at every joint.
It is the imposters who are sent in there and punished in this way.
One night I awoke from sleep and heard around me spirits who had wanted to ambush me while I lay asleep. Soon drifting off, I had a nightmare but then woke up again, and suddenly, to my surprise, found some scourging spirits at hand. They inflicted bitter punishment on the spirits who had plotted against me in my sleep, by giving them a kind of body—a visible one—and physical sensation and then torturing them by violently knocking their limbs back and forth. They also enhanced the pain by inducing resistance. The scourgers fully intended to kill the spirits, if they could, so they used extreme violence.
Most of them were sirens, who are described in Section 831. The punishment lasted a long time and spread out around me to include many other gangs. What amazed me was that all of the spirits who had ambushed me were tracked down, even though they wanted to hide.
Because they were sirens, they tried many tricks for escaping punishment, although they failed at the attempt. First they wanted to slip away to a more hidden plane of existence. Then they wanted to pretend they were someone else. Then they tried to divert the punishment to others by projecting their thoughts. Then they created the illusion that they were babies, whom the castigators were punishing, then good spirits, then angels. They attempted many other ruses too, but all in vain.
Although I was surprised to see how severely they were disciplined, I perceived that this kind of behavior is intolerable because of our need to sleep in safety, since if we could not sleep safely, the human race would die out. That was why the penalty simply had to be so harsh.
I sensed that the same events also occur in the vicinity of other people whom spirits endeavor to attack by stealth in their sleep, although the people themselves are unaware of it. If they are unable to talk with spirits and be present with them by way of an inner perception, they cannot hear, still less see, any such thing, despite the fact that similar occurrences are taking place around them.
The Lord guards us with utmost care when we sleep.
from Secrets of Heaven, Volume 2, Sections 958, 959