It sounds to me like Sleep Paralysis
QUOTE
Sleep paralysis is the experience of waking up (usually form a dream) and feeling paralyzed, except for being able to breathe and move the eyes. Hypnogogic hallucinations and sleep paralysis may occur together. These conditions are common in people with narcolepsy but can also effect others, particularly people who are sleep-deprived. Although a pretty terrifying event, these events are not physically harmful. There are two major types of sleep paralysis: common (typical) also known as CSP and hallucinatory (hypnagogic) sleep paralysis known as HSP.
Differences between CSP and HSP.
CSP is common and universal, HSP is rare and seems to be geographically episodic.
CSP is only unnerving for the sleeper but HSP is accompanied by a nightmare like hallucination.
CSP is of relatively short duration where HSP can last as long as seven or eight minutes.
One of the most important differences between Night Terrors and CSP is that CSPs occurs in Stage one of sleep and Night Terrors occur in stage four.
Different cultures throughout time have interpreted HSPs as different spirits or events.
Ancestral ghosts - Southeast Asians
Hag - Irish and Scottish
Cats - Chinese
Spectral foxes - Japanese
Djinn - Arabs
Guilt - Romans and the Egyptians
Witchcraft - Mexicans
Vampires - Europeans
Demons - Medieval Europe
HSPs are usually a vision of a small creature that sits on the victims chest. The creature then either compresses the chest or attempts to strangulate the victim. Almost all attacks have been reported by people sleeping on their backs.
What is sleep paralysis?
Sleep paralysis consists of a period of inability to perform voluntary movements either at sleep onset (called hypnogogic or predormital form) or upon awakening (called hypnopompic or postdormtal form).
Sleep paralysis may also be referred to as isolated sleep paralysis, familial sleep paralysis, hynogogic or hypnopompic paralysis, predormital or postdormital paralysis
What are the symptoms?
A complaint of inability to move the trunk or limbs at sleep onset or upon awakening
Presence of brief episodes of partial or complete skeletal muscle paralysis
Episodes can be associated with hypnagogic hallucinations or dream-like mentation (act or use of the brain)
Polysomnography (a sleep recording) shows at least one of the following:
suppression of skeletal muscle tone
a sleep onset REM period
dissociated REM sleep
Is it harmful?
Sleep paralysis is most often associated with narcolepsy, a neurological condition in which the person has uncontrollable naps. However, there are many people who experience sleep paralysis without having signs of narcolepsy. Sometimes it runs in families. There is no known explanation why some people experience this paralysis. It is not harmful, although most people report feeling very afraid because they do not know what is happening, and within minutes they gradually or abruptly are able to move again; the episode is often terminated by a sound or a touch on the body.
In some cases, when hypnogogic hallucinations are present, people feel that someone is in the room with them, some experience the feeling that someone or something is sitting on their chest and they feel impending death and suffocation. That has been called the “Hag Phenomena” and has been happening to people over the centuries. These things cause people much anxiety and terror, but there is no physical harm.
What else can you tell me about sleep paralysis?
Some people with disrupted sleep schedules or circadian rhythm disturbances experience sleep paralysis
A study found that 35% of subjects with isolated sleep paralysis also reported a history of wake panic attacks unrelated to the experience of paralysis
Sixteen percent of these persons with isolated sleep paralysis met the criteria for panic disorder
How can I stop the sleep paralysis?
In severe cases, where episodes take place at least once a week for 6 months, medication may be used.
You may be able to minimize the episodes by following good sleep hygiene:
getting enough sleep
reduce stress
exercise regularly (but not too close to bedtime)
keep a regular sleep schedule