I wanted to write a little about Disorders of Sleep vs. Paranormal experiences, and how some Sleep Disorders and/or some components of certain types of seizures might be mistaken for a Paranormal experience. I'm just a Technologist, but I know a little about it, as Sleep Disorders are my specialty. I wanted to just touch upon a few things, and if anyone is interested further, I encourage them to "Google" it.
I would like to recommend the following link: http://en.wikipedia.org/wiki/Hypnagogia
Here are some things that might be mistaken for something "Paranormal":
Sleep Paralysis: that feeling of awakening, not being able to move or speak, having difficulty breathing, and seeing or feeling a presence in the room, such as a ghost, demon, or vampire. Sleep Paralysis is much more likely to occur if you're sleeping on your back. I am not sure why, but it is best to fall asleep on your side or stomach.
"Tetris" effect: example of Tetris effect: you play a video game for many hours, then try to sleep, where you find you feel sensations of still playing it, or dream, seemingly all night long, that you're playing it. Or, you're in a boat all day, then when you lie down to sleep that night, still feel the boat rocking.
Hypnic Jerks: feeling of falling, followed by a body jerk
Hypnagogic and Hypnopompic Hallucinations: hallucinations as you're transitioning from wake to sleep, or from sleep to wake. Typically really scary stuff, like demons, vampires, ghosts.
Confusion Arousals: wake out of Slow Wave Sleep, confused, disoriented, groggy, slow to clear your head.
Night Terrors: (which differ from Nightmares) wake up screaming, confused, frightened, but can't remember a dream or nightmare at all. This typically happens in children, and during that initial period, they will scream and recoil in fear if you try to touch them. They typically have no memory of the episode the next day.
Nightmares: occur during REM (Rapid Eye Movement) stage sleep. The person usually remembers some of the dream, at least initially. The Rapid Eye Movements tend to be more intense in the early morning hours and you're more likely to have intense, long dreams in the early morning right before awakening.
REM Behavioral Disorder: typically seen in older males. Our skeletal muscles our normally paralyzed during REM sleep, to stop us from getting up and acting out our dreams. When this process malfunctions, people get up and act out their dreams. The dreams with this particular disorder tend to be violent, and typically involve fighting off an intruder, or fighting in a war, etc. It's not unusual for people with this Disorder to hurt themselves or their spouse.
Narcolepsy: Narcolepsy usually begins between the ages of around 7 or 8 in to the mid-twenties. About a third of people with Narcolepsy have Sleep Paralysis and Hypnagogic or Hypnopompic Hallucinations, as well as Cataplexy, which is a sudden loss of muscle tone during wake, usually triggered by a strong emotion, such as anger, fear, or even laughter. The person's knees witll typically buckle and they'll fall to the floor. They also have attacks of extreme sleepiness during the day and will fall asleep suddenly, even while driving or having a conversation.
Sleep Walking: typically occurs during the first part of the night, out of Slow Wave Sleep.
Obstructive Sleep Apnea: An obstruction in the upper airway during sleep, causing the person to stop breathing or have limited airflow repeatedly throughout the night. This gives some patients nightmares or sensations of being smothered or choked, or of drowning.
Sleep Deprivation: can cause visual and auditory hallucinations.
Periodic Limb Movements of sleep: a rhythmic jerking of legs and/or arms which occurs approximately every 5 to 90 seconds. This can cause the patient to jerk awake, or cause brief awakenings they may not remember, but will fragment sleep and subsequently cause daytime sleepiness.
Restless Legs: a feeling of creepy-crawliness in your legs, or feeling like your legs are "on speed" while you're sitting and relaxing or trying to go to sleep. Moving the legs or walking helps to temporarily relieve the sensation.
Kleine-Levin Syndrome: a rare neurological disorder that strikes primarily adolescents. The patient becomes more and more drowsy and will sleep for most of the day and night (hypersomnolence), and will only wake up to eat or go to the bathroom. When awake, they are spaced-out or act childlike, confused, and so on. They may be hypersensitive to noise and light. Some patients experience [I]odd[/I] food cravings and/or exhibit "uninhibited hypersexual behavior". The symptoms last for days, weeks or even months. They're not not able to go to school, work or care for themselves. Most are bedridden. People with KLS may go for a period of weeks, months or even years without experiencing any symptoms, but then they'll suddenly reappear. The cause of Kleine-Levin Syndrome is not known.
**warning: adult health-related content to follow:****
During REM sleep, it is normal for both males and females to experience sexual arousal. I have been told by Neurologists I've worked with that this is part of the body's "system maintenance" in a manner of speaking. It is normal and healthy sign for a man to awaken with an erection, fresh out of REM sleep, and for a woman to awaken with a sexual arousal as well. As a matter of fact, when a man stops having early morning erections, and is having erectile dysfunction during sexual intercourse, this is a clear indication that it is due to a real physiological problem, (as opposed to some psychological issue). I mention sexual arousal during REM stage sleep because it may be related to what people perceive as a Paranormal experience. Example: They're in REM, having a nightmare, the body has paralyzed itself to stop them from getting up and acting out dreams, the body has also caused a sexual arousal in their, ahem, "nether-regions". The person awakens out of REM too quickly, the effects of REM have not worn off yet. They're paralyzed, frozen still, and having waking-dreams, hallucinations of scary things, like a demon or a Succubus or something, and this "demon" touches them in a sexual manner...... A very possible and likely explanation is, they're paralyzed because they woke too quickly out of REM, which is the stage of sleep where the body is supposed to be paralyzed. They're seeing scary things in the room because they woke out of REM too quickly they're essentially dreaming while awake. The so-called "demon" in the room is sexually molesting them because the human body, in REM, gets sexually aroused as a normal component of REM, and so when they woke out of REM too quickly, the body is still sexually-aroused, causing this waking-dream to sometimes have a sexual theme.
I believe it can be accurately said that many (not all, of course) experiences people have during the night or early morning, and even during the day or during Naps can be attributed to Disorders of Sleep, as well as at least some of these experiences being caused by certain types of seizures (such as simple partial or complex partial seizures) that can cause visual, auditory, gustatory, and olfactory hallucinations and sensations. People will see, hear, taste, smell things that are not real. They may also feel a sense of deja vu before a seizure.
I hope this gives some people a sense of relief and some comfort knowing that some of that really scary stuff that happens at night and early morning may not be Paranormal.