You awake suddenly at night. You try to rise, but feel hands pressing down on your chest, groping for your throat. You try to cry out, but you cannot move or speak. You notice a shadowy figure at the foot of the bed, and hear the steady clomp, clomp, clomp of others climbing the stairs to your room. Your terror grows, but then as suddenly as it began, the pressure releases and the presence in the room fades into nothingness. You can now move, rise from the bed, and try to make sense of what just happened to you. You have just had an episode of sleep paralysis.
Normally, when you dream, you are paralyzed. This is handy, because without this you would regularly act out your dreams. In sleep paralysis, however, the normal cycles of your sleep become out of sync: your mind wakes up, but your body is still in a dream state. You are aware of your surroundings, but cannot move and may also experience any number of hallucinations. Most commonly, these hallucinations include sensing the presence of others (including seeing shadowy figures), feeling external pressure on the chest, hearing odd knocking sounds, seeing your body as if from the outside, or experiencing vibrating or tingling sensations. Any single episode of sleep paralysis may include one or more of these hallucinatory symptoms.
Between 6 and 17 percent of the general adult population experience sleep paralysis at some point in their life and it is even more common among certain groups. For example, higher rates are reported among college students (near 30%). This might be because of the common sleep disruptions that college students experience (all that late night studying, no doubt); sleep paralysis occurs more often following sleep disturbances. Overall, sleep paralysis is normal, and comes with a good scientific explanation. Yet, the experience of sleep paralysis can be terrifying, particularly when a person does not understand what is going on.
And without a good explanation, many will search for a more supernatural explanation for their harrowing experience. The odd knocking sounds could be the sound of a machine or someone climbing stairs or knocking at the door. The sense or vision of a presence and the feelings of chest pressure can be taken for a ghost, demon, or alien leaning over and pressing on the chest or throat, or sitting directly on the chest. The particular kind of supernatural explanation for these symptoms often depends on a person's culture. In Japan, these experiences may be known as a kanashibari attack. In Newfoundland, it might be interpreted as the action of the "old Hag" sitting on the chest, or in the West Indies the attacking spirit is known as Kokma. A web search of any of these terms will reveal strikingly similar accounts of the symptoms of sleep paralysis.
Also included among the interpretations of sleep paralysis is an account that has been particularly endemic to the United States - alien abduction. Think of the symptoms of sleep paralysis: a sense of one or more beings lurking over the bed, feeling held down by some power, feeling electrical vibrations or sensation of numbness or floating, and of course the paralysis and feelings of fear. Then, just as suddenly as they appeared, these images and sensations fade, and one is left alone in bed, trying to make sense of what happened. It sounds a lot like a Spielberg movie to me. And it is easy to see that in trying to explain this experience some may turn to ghostly hauntings, some to angelic apparitions, some to worries about neurological disease, and some to alien visitation. Some will come to these interpretations on their own, and some will be given an explanatory context by the media or the web, or friends or family. Still others will just pass off the experience as a random weird event.
Hence, there are two parts to the sleep paralysis experience: (1) the immediate experience of symptoms, and (2) the potentially long-term change in beliefs about the world that result from interpretations of that event. Understanding the symptoms of sleep paralysis, and knowing that they need not be interpreted as a sign of the supernatural (for good or for evil), can help keep temporary symptoms from becoming a life-altering event.
Copyright Michael W. Otto
Dr. Otto is author of Exercise for Mood and Anxiety Disorders: Proven Strategies for Overcoming Depression and Enhancing Well Being, and Living with Bipolar Disorder, as well as treatment guides for clinicians.