Explaining Sleep Paralysis
Sleep paralysis can be 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: sleep paralysis is characterised by the inability of the person to move their muscles.
Sleep Paralysis: A Frightening Experience
Unfortunately, sleep paralysis can be accompanied by frightening hallucinations 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.
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 apnoea, and anxiety disorders. When a person sleeps in a fixed supine position, it increases the likelihood of them experiencing sleep paralysis. In addition, sleep paralysis is related to REM atonia, which is the paralysis that occurs as a natural part of REM sleep.
When Does Sleep Paralysis Occur?
Sleep paralysis occurs 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 sleep paralysis 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.
Sleep Paralysis Is Not Complete Paralysis
Due to the correlation of the paralysis with REM sleep, this type of paralysis 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 sleep paralysis is not able to speak.
Types of Visions
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 of sleep paralysis as a sense of terror; where they experience sleep paralysis 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.