I do know exactly what you're talking about as I've had similar experiences.
Back in high school when my paranormal abilities were at their most heightened state I ended up in a very long battle with a demon and there were a few times when I experienced what you're talking about, where something was strangling me in my bed and I knew I would die in real life if I didn't get free.
I didn't know it then, but I was vibrating in a fear state so I was attracting all of these negative entities and experiences to me. If I were you, I would work on raising your vibration to a state where these entities cannot reach you. YOu've got to close the door on them, so to speak.
Cleanse your chakras, call upon the archangel Michael, and ask your guides to assist you whenever you are feeling fear.
Now I know you said you are not afraid... neither was I. I was determined to take that demon down, and eventually I did (took about 4 months though). But the truth is that I was resonating with a fear energy and attracting them to me.
It's okay to fight demons, but it can be exhausting and it can really drain your energy. So be careful out there. You might want to ask your guides why the demons are attacking you. Could be insightful.
Erin Pavlina, Intuitive Counselor
Connect with me on: Facebook