Sleep paralysis is a medical phenomenon where awakening person experiences temporary inability to move or speak. It is a state between being asleep and awake, where one’s mind is awake but the body is still sleeping. It usually lasts only a couple of seconds or up to one minute, but one can get a feeling it lasts much longer (several minutes). It usually happens very rarely and almost always when sleeping on its back. Regularly, person can experience panic attack and severe paranoia during this state, as the feeling of helplessness intensifies.
There is also another form of sleep paralysis, but significantly rarer, sometimes even more than once per night, and if you are hit by this form of sleep paralysis you might feel trapped in your body for more than an hour!
In this phenomena if the person experiencing sleep paralysis opens its eyes, he or she might experience visual and/or audio hallucinations, usually thinking the “intruder” is in the room where intruder either can’t be seen or can be seen in a form of some demon or dead relative. This is usually accompanied with the feeling of inability to breathe, which is usually described as “the witch sitting on your chest”.