Dr. Chris French of the Anomalistic Psychology Unit at Goldsmiths College is currently writing a piece on sleep paralysis and would like to illustrate it with a few vivid personal accounts from sufferers. Sleep paralysis, in its most basic form, refers to the common experience that many people have of being half-awake and half-asleep, and realizing that one cannot move. That in itself can be quite scary. But it's sometimes accompanied by visual and/or auditory hallucinations, a strong sense of presence, pressure on the chest and difficulty breathing, and intense fear. Sleep paralysis can be extremely upsetting but is essentially harmless. However, it is often misinterpreted as a visitation by spirits or aliens.
If you have had such an experience, Dr. French would love to hear from you - preferably with a nice description of your experience about 200-300 words long. Email him at firstname.lastname@example.org