Sleep Paralysis

Sleep paralysis is a state in which the individual is conscious, but feels that they are not able to move. The person often feels that they cannot speak nor move their muscles, but that they are conscious. Sleep paralysis often occurs in the passage from being asleep to awake. Sleep paralysis can be very unpleasant and frightening. Some may also experience certain hallucinations as if they were having a nightmare, for example, seeing someone scary enter the room or as if someone is touching them. 

When you are sleeping you go through a set of stages throughout the night, sleep paralysis could happen due to your brain not properly handling the transition of going from the sleeping stage to being fully awake.

In many cases sleep paralysis does not call for treatment and can be caused by natural factors. Changes in your sleeping schedule can be a trigger of sleep paralysis. Also factors like going on certain medication, not getting enough good sleep and bad sleeping positions (on your back) are all rather normal things, but could trigger sleep paralysis.

In some cases, the key to fix your problem with sleep paralysis could be to attack a different problem, seeing as though in some instances the sleep paralysis could be a byproduct of a different issue. If you have mental health issues, seeking therapy could help you with sleep paralysis. Narcolepsy, a condition where your sleep and awake cycle is severely reduced, could heavily cause sleep paralysis, seeing as though it reduces one's quality and amount of sleep.

References:

Sharpless, B. A., & Doghramji, K. (2015). Sleep paralysis: historical, psychological, and medical perspectives. Oxford University Press.

Sharpless, B. A., & Barber, J. P. (2011). Lifetime prevalence rates of sleep paralysis: a systematic review. Sleep medicine reviews, 15(5), 311-315.