I've experienced Hypnagogic/Hypnopompic hallucinations before there really scary. Sometimes it only lasts a few minutes but its awful. I would be lying down and I couldn't move when I'd hear the sound of breathing so I'd look to the side of my bed and realize that there was a figure of a man standing over me and watching. I would be petrified!

I learned though while reading that you can help yourself during one of these moments by clenching your fists or moving as much as you can to remind yourself that is not real! Even though at the time it will feel like it. Also as soon as your able put a light on and the feeling will disapear. I hope this helps