It seems like using a sigil under the pillow, somehow affect the head chakra, connecting the astral ability of Clairsentient momentarily. Momentary possesion seems also to appear sometimes.
Now, I don’t use sigils under my pillow, but I experience similar events with my spirits. Every. Single. Night. I love it!
For those who are unsuccessful evoking Lilith or succubus/incubus entities, maybe should try to use Lilith’s sigil and the Letter Of Intent - How To Evoke A Succubus/Incubus *update* under the pillow and burn it the day after. 