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There are likely not many experiences more terrifying than an episode of sleep paralysis. Waking in a darkened bedroom, unable to move, with the feeling that an evil entity is in the room – sometimes even in bed with you.

Sleep paralysis experiences occur across the globe, and are in many cases interpreted as supernatural – and that belief is so powerful in some cultures that it has the power to kill. Modern science, on the other hand, believes it is all to do with the brain not quite working as it should during the sleep experience.

But plenty of mystery still surrounds sleep paralysis, mainly due to the lack of serious study that has been undertaken to better understand the phenomenon. As a recent paper notes, sleep paralysis continues to receive “more attention from the unscientific world”, and furthermore, the stigma associated with it “has also prevented sufferers from reporting at medical institutions”. As such, researchers note, “most sufferers revert to other confidential means such as herbalists, religious leaders, and traditional priests for a solution”.

The short paper, “Sleep Paralysis, a Medical Condition with a Diverse Cultural Interpretation“, therefore concludes that “it is important to sensitize the public on what sleep paralysis is and how it should be approached.”

It begins by outlining modern science’s view of the terrifying aspects of the phenomenon:

The phenomenon of a dream happens in the REM phase of sleep, where there is no motion or muscle activity. We tend to have our most emotional dreams during REM sleep, and to stop us from acting out these dreams, the brain keeps us temporarily paralyzed.

In REM dreams, another structure that has a major role to play is the limbic system. The limbic system consists of the hypothalamus, hippocampus, amygdala, septal nuclei, cingulate, different thalamic nuclei and portions of the reticular activating systems, orbital frontal lobe, certain cerebellar nuclei, among others. Amygdaloid complexes according to research have shown to process memory, decision-making, and emotional reactions. The lateral amygdala sends impulses to the rest of the basolateral complexes. This is preceded by the activation of the amygdala through projections from the thalamus, anterior cingulate, and structures in the pons. This gives the individual the idea that an intruder is in the room. This complex pathway (subthalamo–amygdala pathway) is responsible for ensuring that in moments of danger there is an appropriate response in the body without the need for in-depth analysis by the sensory cortex.

The paper then goes on to point out the varying ways that sleep paralysis is experienced, and interpreted, across the globe. It notes that while the occurrence of sleep paralysis in the general population is about 8%, in some cultures it appears to be much higher. For instance, a study in Japan found that 40% of the general population experiences sleep paralysis.

And there is a wide variation in how it the phenomenon is interpreted in different locations. The researchers list a number of culture-specific interpetations in a table attached to the paper: in Newfoundland, they know it as the ‘Old Hag’, while in Egypt it is thought to be a Jinn attack. In Korea it is Ha-wi-nulia, which means “being squeezed by scissors”, and in Japan it is kanashibari, interpreted as a person feeling helpless in coping with external forces.

The paper also notes that the different interpretations of sleep paralysis also result in different ways of coping with it. For example:

Chinese people usually approach SP by employing the help of a spiritualist. Italians, on the other hand, believe sleeping facedown and placing a broom by the door with a pile of sand on the bed will help prevent SP.

Do you suffer from night terrors? If so, what do you do to cope with it?