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Symptoms of Sleep Paralysis

Inability to Move, Hallucinations and Fear Are Common

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Updated May 16, 2014

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YOUNG WOMAN LYING IN BED AWAKE
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Sleep paralysis is a relatively common experience, but it can still be extremely frightening if you don’t know what it is. What are some of the symptoms of sleep paralysis?

Defining Sleep Paralysis

First, it is important to understand what sleep paralysis represents. In simple terms, sleep paralysis is the presence or persistence of features of rapid eye movement (REM) sleep during the transition into or out of deep sleep. It may occur when you are first falling asleep (hypnagogic) or when you are waking up (hypnopompic). Most people experience just sleep paralysis, but it can also occur with other symptoms as part of narcolepsy.

During REM, your mind is active and you might vividly imagine sights, sounds and other feelings as part of a dream. You might even be afraid, as you would in a nightmare. At the same time, your body is paralyzed so that you do not act on your dreams (this is called muscle atonia). When these features occur during wakefulness, you will have an experience of sleep paralysis.

Common Features of Sleep Paralysis

Sleep paralysis is often characterized by a transient inability to move or speak during sleep transitions. In general, the ability to move your eyes is preserved. Some people try to scream or call out for help, but this may manifest only as a soft vocalization. For example, you might only be able to whisper, squeal, grunt, groan or whimper.

Many people have a sense of suffocating or breathlessness during sleep paralysis, which likely relates to the limited muscles that are active to help you breathe. During REM sleep, the diaphragm acts as a bellows to help you inflate your lungs and breathe, but few of the other accessory muscles of breathing are active. Some people experience this as a chest pressure or as if someone is standing or sitting on their chest.

The level of awareness during sleep paralysis varies. Some people insist they are completely awake and aware of their surroundings, while others describe only a partial awareness. Infrequently, people may have an out-of-body experience, the belief that they are outside of their bodies looking at themselves.

The Important Role of Hallucinations

Vivid hallucinations may be part of this experience. In other words, you perceive an experience of something that is not there. In a broad sense, the hallucinations associated with sleep paralysis can be divided into visual, auditory, olfactory and tactile experiences.

The visual experience can be quite profound. Many people report seeing the presence of a human figure, often described as being a dark figure, shadow or ghost. This figure may be standing at the bedside, just at the periphery of your vision. Some people report seeing multiple people in the room. Others report that they see flashes, bright colors or lights. Sometimes the visual hallucination can be quite elaborate. For example, some have reported seeing a disembodied hand, a gargoyle, bugs or even a cat. In other cases, the visions are vague, described as being blurry or shimmering or simply having a sense that things are floating.

Similarly, the experience of auditory hallucinations in sleep paralysis can range from the routine to the bizarre. Many people hear various noises. It is most common for people to hear voices. The language used might seem foreign. There may the perception of whispering, screaming and laughing. Nearly as often, a loud buzzing or static noise is reported, much like the sound of a radio that is on but not tuned to a station. Some people hear breathing, footsteps, knocking or a ringing sound. Even unusual sounds like a horse carriage or growling may be perceived. Sometimes the sounds heard during sleep paralysis are nonspecific, difficult to characterize or not well remembered.

One of the most often reported phenomena of sleep paralysis is a tactile hallucination, the experience of being touched when you are not. Many people describe feeling a pressure or contact, often sensed as if something or someone is holding them down. Some people with sleep paralysis describe tingling, numbness or a vibrating sensation. Others describe a sense of floating, flying or falling. A few people report feeling chilled or freezing. Less frequently, there may even be a sense that you are being physically moved or dragged from your bed. Some people report sexual contact, including physical sensations involving the genitalia or even rape. Other physical experiences have been reported as well, including a sense of being bitten, bugs crawling on the skin, breathing in the ear or an uncontrolled feeling of smiling.

The least common hallucination in sleep paralysis is of an olfactory nature, relating to your sense of smell. As with the other types of hallucinations, you could imagine a range of possible imagined smells that you might experience.

The Emotional Component of Sleep Paralysis

Aside from the experiences described above, one of the most important and lasting elements of sleep paralysis is the emotional component. For many, the experience of a sleep paralysis is a waking nightmare. The perceived dark figure in the room seems to be an evil presence, intent on real harm. The stranger standing over you or sitting on top of you is up to no good.

The vast majority of people who experience sleep paralysis describe it as a fearful experience (scary, terrifying, horrifying, frightening, etc.). This is often associated with the hallucination of a stranger’s presence. Some people have a sense of impending doom, meaning they have a feeling that real harm or death is about to occur to them. Many describe how real everything seems when it is occurring. It is not uncommon for people to use the words "weird" and "strange" to describe their experiences. There are a variety of other descriptors used by people to summarize their sleep paralysis, including: helpless, shocking, worried, angry and disgusting. Rarely, people may actually be comforted by the experience.

By having a better understanding of the common symptoms of sleep paralysis, you may be able to take comfort in knowing what is happening to you. For some people, this is enough to tolerate these infrequent occurrences. For others, this knowledge may help to eliminate triggers of sleep paralysis. For those who find these episodes particularly distressing, effective treatment options are available.

Sources:

Kryger, M.H. et al. "Principles and Practice of Sleep Medicine." ExpertConsult, 5th edition, 2011.

Morton, K. "Paralyzed at Night: Is Sleep Paralysis Normal?" Stanford Sleep & Dreams. 2010.

Spanos, N.P. et al. "The frequency and correlates of sleep paralysis in a university sample." J Res Pers. 1995;29:285-305.

Takeuchi, T. et al. "Factors related to the occurrence of isolated sleep paralysis elicited during a multiphasic sleep-wake schedule." Sleep 2002;25:89-96.

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