Do you know about Sleep Paralysis? I have experienced it many times while sleeping. In case of sleep paralysis, one can be alert or hear or feel everything but can’t be able to move his/her body. You can experience this symptom in two conditions either you are in a state of sleep or when you get up from sleep. In a state of sleep paralysis, various unusual things that actually don’t exist can be seen or heard by people. It is harmless and may continue for one or two minutes. Sometimes it goes away within few seconds.
Usually, when you are in state of sleep, your body muscles get relaxed. This condition is known as “atonia”. If atonia happens on the time of awake, it is called sleep paralysis, because you can hear, feel and understand everything, but don’t have enough power to move your body organs like leg, hand, head and body. You won’t feel any disturbance in breathing process. So there is nothing to worry. However it continues for few seconds or minutes, it can be terrible for one. Generally, this condition gets terminated automatically. Someone’s touch or call can also help you come out from Sleep Paralysis. This episode can also be discontinued if you try hard to move your body organ. I always tried last option whenever I fell into this condition.
There are various factors that can stimulate Sleep Paralysis like sleep disorders, experiencing huge stress or having not enough sleep. Sleep Paralysis may also cause hallucination, a condition in which people start seeing, hearing or feeling such things that actually do not present there. They can also get feared not able to move their body organs.
However you may experience it once in your lifetime or many times in a year, it is not harmful for you.
Source: https://en.wikipedia.org/wiki/Sleep_paralysis
http://www.sleepeducation.org/sleep-disorders-by-category/parasomnias/sleep-paralysis/overview-facts