Sleep Paralysis - The Basics

What You Need To Know
Sleep Paralysis is a natural bodily function that causes us to be paralyzed during sleep. It prevents us hurting ourselves or others during dreams. It's when it follows us into the waking state that it becomes a disorder.
SLEEP PARALYSISSYMPTOMS
Inability to move the trunk or limbs. This can occur at sleep onset or upon awakening.
Hallucinations.These can be visual (You think you see something,) or Auditory (You think you hear things.) In some cases, the sense of smell is also involved.
Feeling of pressure. Like someone sitting on you or holding you down. Fear Even outright terror may be involved.
Occasional sensations of being Out of Your Body (OBE.) Floating or flying through the air. Feeling disconnected from your body.
CAUSES
A natural state: Sleep Paralysis is a natural bodily function that causes us to be paralyzed during sleep. It prevents us hurting ourselves or others during dreams. It's when it follows us into the waking state that it becomes a disorder.
Stress and anxiety.
Narcolepsy.
Sleeping on the back.
Puberty.
Bipolar Disorder.
Depression.
METHODS OF DIAGNOSIS
Personal Experience
Observation by roommates
Sleep Study
AVOIDANCE
Talk to your doctor. He may be able to prescribe something to help.
Keep on a regular schedule. Go to bed, get up and eat meals at regular times.
Get some exercise. Even a short walk earlier in the day can help.
Avoid sleep deprivation.
Alleviate the stress in your life.
Know you are not alone.
Relax. You are not dying or going insane. As far as is known, sleep paralysis is not harmful.
Read David Hufford's book. "The Terror that Comes in the Night" can help you understand this strange disorder.
FINDING RELIEF
When you realize you are having an attack:
Will yourself to move a finger or make a sound.
Scream. If it doesn't wake you, it will at least alert others to your distress.
Go with the flow. If all else fails, relax and It will soon pass.

http://sleepdisorders.about.com/cs/sleepparalysis/a/paralysisbasics.htm