It is a very frightening story that many of you have experienced: You awaken in the morning, but are unable to move your body. This is the story and description of ‘Sleep Paralysis’.
Sleep paralysis is a sleep/wake phenomenon that most people experience in their lifetime. Usually it occurs in the morning, upon awakening. However, it can happen during other transitions between wake and sleep. In most cases, it is a normal finding. For some, though, it is a symptom of the sleep disorder, narcolepsy.
Often the sensation can be accompanied by intense fright and fear because the individual feels completely paralyzed during sleep. The experience is usually short-lived lasting only a few seconds.
Theories of Sleep Paralysis
It has been theorized that we evolved to be paralyzed during dream sleep in order to protect ourselves and the ones near us from bodily harm. This makes sense as we would not want to thrash and kick while sleeping.