It's called sleep paralysis. And it usually feels like being awake in a nightmare. Many a demons, across cultures have been blamed for this sleep disorder, which is pretty common. I'm not trivialising the experience. It feels very real and sometimes makes you phobic about going to sleep. You either feel pulled in one direction or pushed into the bed. It feels as though someone is sitting on your chest. You have difficulty breathing. And when you want to scream, your voice betrays you. And it usually happens when you're sleeping flat on your back. In some cases, the paralysis is accompanied by dreams or hallucinations of sexual assault. But be rest assured that this can be dealt with. Please do some research on Sleep Paralysis, it will prevent you from going out of your mind.
In another thread with a similar subject I had given a few tips on how to come out or wake up from Sleep Paralysis. Just thought I'd copy-paste it here. Hope it helps
1. Don't Fight
If you feel like you are being held down and you can?t move, do not fight back. This will intensify the experience. Not only is fighting back likely to increase the feelings of being held down (so much that it may seem like you are being crushed), but fighting back will also increase the fear, triggering emotional centers of the brain and strengthening this lucid nightmare, which can sometimes create hallucinations of demons. Controlling fear is the most important part during these moments. Instead, try to relax and tell yourself ?This is a sleep paralysis, it is temporary, it will pass and I am okay.?
2. Feeling pressure on your chest?
Don?t push against it. If you feel like a pressure on your chest is pushing you into the bed, relax and mentally ?pull? in the direction I am being pushed. What happens is I then ?pop? into a full-on dream, or I can wake up directly.
3. Small movements
Wiggle your toe, finger, clench your feet. Most of the feelings of paralysis are in the trunk of your body. So focus In many cases, this will break the paralysis.
4. Focus on your Breath
An easy way to stop these nightmares is to do some controlled breathing. Controlled breathing does several things at once. For starters, it lessens the feelings of chest pain that sometimes accompany SP. Breathing is autonomic like the heart?s beating or digestion, so it?s not paralyzed like the big muscles in our arms, chest and legs. But breath can be controlled with attention or be affected by severe fear, which may be why sleep paralysis sufferers ?forget? to breathe when under attack. If you can control your breath, you can control your fear. Simply draw your breath in at a normal rate, and exhale fully, using all of your lung capacity. Notice that you can breathe fully without obstruction. This technique will keep you calm as the SP runs its course and then you will wake up without any trouble. A few moments of focused breathing with a strong intention to wake up is effective.
5. Think of someone or something that calms you down
Think of someone or something you associate with peace, love and safety. This could be Jesus, the Dali Lama, Archangel Michael, a poem, a song, a candle flame, a prayer or even someone you know personally, like your grandmother. This will help you relax.
Like breathing, coughing can be autonomic or consciously regulated. By coughing on purpose, you can jar yourself awake.
7. Make faces
When you realize you are in sleep paralysis, scrunch up your face. In other words, make a face like you just smelled something bad. Snarl and squint. Do this two or three times in a row and the paralysis will break. This is apparently full proof
8. When you wake up
After you wake up, get out of bed immediately and turn on a light. Wash your face with cold water and have a glass of milk. If you just stay in bed, the chance of sliding right back into sleep paralysis is pretty high.