Well, because the information I have found on this topic has come from chapters 11-12 of "Sleep Disorders for Dummies", I will present their study even more briefly, while still following their outline. Sorry for all the quotes.
Sleepwalking/talking and some other strange nightime activities are known as parasomnias and are quite common, especially among children (about 10% of adults). The line that quickly caught my attention was, "We cover parasomnias that produce physical behavior ranging from sitting up in bed and looking confused to leaping out of bed and jumping through a window (the dreaming person thought she was diving into a lake)."
Causes: "Like many other conditions, stress and/or fatigue can precipitate or worsen parasomnias. Parasomnias can also result from overindulging in alcohol, or as a side effect of some medications. Sleep deprivation can trigger many parasomnias." Possibly genetic.
Sleepwalking: about 30% of children and 5-7% of adults. "If onset occurs in adulthood, the disorder likely persists for the rest of the person's life."
*"Most sleepwalkers experience one or two episodes a month, and rarely have more than one episode a night. However, some people sleepwalk almost every night and, as a result, suffer from sleep deprivation. If you sleepwalk, regularly sustain injury, and often feel sleepy during the day, seek treatment for your condition."
Sleep talking: can show up as a symptom of other sleep disorders (ie. night terrors).
Well, that's all I'll share from chapter 11, but I will say that the symptoms they listed and the description of the parasomnias lined up almost identically with what I was already aware of, so that was enough credentials for me.
On to chapter 12 "
Night Terrors and Other Frightening or Unpleasant Sleep Problems"...
"Sleepers may awaken terrified and inconsolable when they experience an episode of parasomnia like night terrors. Their hearts are racing and they're completely panicked. The fascinating thing is that often the person is unable to explain what was so frightening. The sleeper may go back to sleep and awaken the next morning with little or no recollection of the episode."
Nightmares and terrifying hypnagogic hallucinations (images that occur when a person is falling asleep) can seem so real that the person may hurt themselves while trying to flee, or may attack whoever is with them.
Difference between night terrors (NT), terrifying hypnagogic hallucinations (THH), and nightmares (Nm) (This is found in a table format in the book):
NT - not associated with dreaming.
THH - sleeper can recall some details and remembers being unable to move and/or feeling crushed.
Nm - occur during dreams.
NT - sleeper has little or no memory of the episode.
THH - associated with a dream of a being or monster often sitting on the dreamer's chest, possibly sucking the life force out of him or having sex with him.
Nm - sleeper easily recalls details of this scary dream.
NT - disoriented and confused upon awakening.
THH - sometimes disoriented but not usually.
Nm - no disorientation or confusion upon awakening.
NT - may be accompanied by sleepwalking.
Thh - no sleepwalking.
Nm - no sleepwalking.
Causes: Exact cause unknown. Believed the origin is usually physiological (ie. sleep deprivation, lack of regular sleeping schedule). Stress and anxiety can also trigger NT. "Psychological factors ususally play a minor role. Nonetheless, in rare cases, sleep terrors can result from a traumatic experience, the memory of which may even be surpressed during wakefulness." Certain medications could increase NT, "especially if you stop taking them suddenly. Alcohol and drug abuse can also make you more susceptible. Possibly genetic.
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When Sleep Turns Violent - REM Sleep Behavior Disorder" (RBD). "About 2% of all sleepers suffer from RBD, or episodes of violent, aggressive behavior during the night. These episodes aren't only distressing, but can also be very dangerous for both the sleeper and his bedmate....The risk of RBD increases with age....In RBD, something goes wrong with the mechanism that paralyzes [in a good way] the body. The result: As you begin to dream, you actually act out your dream. You may be dreaming that you're playing football and leap up from bed and tackle your dresser, run headfirst into a wall, or dive over the goal line that in reality is your bathroom....RBD differs from sleepwalking because the actions are in response to the dream content, and you can recall, sometimes in great detail, your dream upon awakening. Also, you're acting on the dream's content, not in the real world. So for instance, a sleepwalker can walk over to a window, open it, and step out. By contrast, in RBD, you may leap through the window dreaming about diving off a diving board into a pool."
Symptoms: "When a person with RBD enters REM sleep, he may start to violently act out his dreams. He may kick, punch, jump, get up, run away from the bed, or engage in other intense physical activity. He is difficult to awaken, and violent and combative when approached by another person."
