Sleep paralysis is characterized by the sensation of being unable to move while awakening from sleep. Sleep paralysis is described as a transitional state that occurs when a person experiences a temporary inability to react, move, or speak while asleep, falling asleep, or on awakening from sleep.
Symptoms of Sleep Paralysis
Unfortunately, sleep paralysis can be accompanied by frightening hallucinations during sleep whereby, due to the paralysis and physical experiences (which could be a forceful current running through the upper body), the person is left physically unable to react. These hallucinations can be very scary, and often involve a supernatural creature or other person taunting or terrifying the individual, together with difficulty breathing and/or a feeling of pressure on one’s chest. Another quite common type of hallucination involves either supernatural or human intruders lurking outside the person’s window or entering their bedroom, leaving the sleeper with feelings of fear and dread.1
During sleep paralysis, the individual is completely aware of the surroundings. The person often has the desire to move but is unable to. It can be frightening to the person.
What Causes Sleep Paralysis?
One explanation of sleep paralysis is that it’s caused by disrupted REM sleep: REM sleep typically induces total muscle atonia which prevents sleepers from acting out their dreams. Sleep deprivation and genetics are the major causes of sleep paralysis, and this condition has also been linked to disorders such as migraines, narcolepsy, obstructive sleep apnea, and anxiety disorders. It is associated with excessive daytime sleepiness and being sleep deprived. When a person sleeps in a fixed supine position, it increases the likelihood of them experiencing sleep paralysis. In addition, it is related to REM atonia, which is the paralysis that occurs as a natural part of REM sleep. Sleep paralysis is also one of the symptoms of narcolepsy.2
When Does Sleep Paralysis Occur?
These events often occur when a person is either falling asleep or awakening from sleep. If it occurs when going to sleep, the person will remain alert while the body prepares for REM sleep. This condition is known as predormital or hypnagogic sleep paralysis. If it occurs when the person is waking up, the person becomes alert prior to the REM cycle being completed. This condition is known as post-dormital or hypnopompic paralysis. The events can last anywhere from a few seconds to a few minutes, with rare cases lasting for hours, where the person could well experience panic symptoms.3
Sleep Paralysis Is Not Complete Paralysis
Due to the correlation of the paralysis with REM sleep, this type of atonia is not complete. The use of EOG traces clearly show that eye movement is still possible during these episodes; however, the person who is experiencing the events is not able to speak.
Types of Visions Associated with Sleep Hallucinations
The three main types of visions that have been linked to pathologic neurophysiology are –
- Vestibular motor sensations,
- The incubus, and
- Believing there’s an intruder in the room.
Many people describe their experience as a sense of terror; where they experience the events followed by the sense of a frightening presence (or intruder) in their room. The neurological explanation for this phenomenon is that sleep paralysis occurs due to a hypervigilant state created in the midbrain. Specifically, the brain activates the emergency response when the person wakes up paralysed and feeling vulnerable to attack. This feeling of helplessness only serves to intensify the brain’s threat response, certainly more so than the level associated with normal dreams. This could well explain why visions experienced by a person during sleep paralysis are so clear and graphic.
Sleep Paralysis: The Story of Being Awake but Unable to Move
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
Many scientists believe that sleep paralysis occurs because of ‘cross-over’ between different sleep stages. Specifically, there is a transition that occurs between REM sleep and wake.
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.
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