Well hell. My description sucks compared to
this one:
<blockquote>The <b>Common Sleep Paralysis</b> happens, for most people, during R.E.M. state, when the body releases hormones that paralyze to keep it from acting out dreams, thereby reducing any chances of physical harm during sleep. It is a safety net. These hormones usually wear off before the dream ends and the person will then wake up with full use of all body functions. The Common Sleep Paralysis usually only lasts from seconds to 1 minute in total, though sometimes it can go a little longer.
The <b>Hallucinatory/'Hag' Sleep Paralysis</b> is experienced when 'hypnologic' (inability to perform voluntary movements during sleep) hallucinations are present after the person has awakened from sleep to find their body paralyzed. During these times, a person will feel a presence in the room with them (the 'Hag') - usually an evil or fearful presence. Some go further and feel as though someone or something is actually sitting on them and they feel as though they are suffocating or dying. Experiencing this can cause a person much anxiety and fear, but, again, there is no physical harm involved.
The Hallucinatory Sleep Paralysis is different from Common Sleep Paralysis because it can last up to 8 minutes long (sometimes longer) and, due to nightmarish hallucinations, is usually an extremely frightening experience. To the person caught in this state, it is extremely realistic and very intense.</blockquote>