question: What actually happens when we unintentionally start to drift off to sleep but our body suddenly "shocks" us awake?
comment: From my understanding of some theoretical model of how sleep works, and explained in the way a 5-year-old who understands enough to ask this question: & #x200B; The different parts of your brains that control what you do talk to each other through waves of electricity when you're awake. When you start to sleep, one big sleep wave goes over your whole brain so the different parts of your brain can't hear each other anymore over this big wave. When you feel like you're falling asleep little by little, almost rhythmically, that is the sleep wave trying over and over again to stop the parts of your brain from talking to each other. When you suddenly wake yourself, that's one or more parts of your brain sending waves out "louder" because they don't know why they can't talk to the other parts anymore. Then the big sleep wave has to try again, and hopefully it will stop all of the different parts of the brain from talking to each other, so there's just one big, rhythmic wave and you can get some sleep! & #x200B; **^(EDIT:)** ^(Formatting, and a few extra words for clarity.)
passages: The majority of sleep neurons are located in the ventrolateral preoptic area (vlPOA). These sleep neurons are silent until an individual shows a transition from waking to sleep. The sleep neurons in the preoptic area receive inhibitory inputs from some of the same regions they inhibit, including the tubermammillary nucleus, raphe nuclei, and locus coeruleus. Thus, they are inhibited by histamine, serotonin, and norepinepherine. This mutual inhibition may provide the basis for establishing periods of sleep and waking. A reciprocal inhibition also characterizes an electronic circuit known as the flip-flop. A flip-flop can assume one of two states, usually referred to as on or off. Thus, either the sleep neurons are active and inhibit the wakefulness neurons, or the wakefulness neurons are active and inhibit the sleep neurons, Because these regions are mutually inhibitory, it is impossible for neurons in both sets of regions to be active at the same time. This flip-flop, switching from one state to another quickly, can be unstable.
   Section::::Brain activity during sleep.:NREM sleep activity.:NREM 2.
  
  NREM Stage 2 (N2 – 45–55% of total sleep in adults): In this stage, theta activity is observed and sleepers become gradually harder to awaken; the alpha waves of the previous stage are interrupted by abrupt activity called sleep spindles (or thalamocortical spindles) and K-complexes. Sleep spindles range from 11 to 16 Hz (most commonly 12–14 Hz). During this stage, muscular activity as measured by EMG decreases, and conscious awareness of the external environment disappears.
  
  Section::::Brain activity during sleep.:NREM sleep activity.:NREM 3.
   While You Were Sleeping
  
  While You Were Sleeping may refer to:
  
  Section::::Film and television.
  
  BULLET::::- "While You Were Sleeping" (film), a movie from 1995
  
  BULLET::::- "While You Were Sleeping", an episode from TV series "Elementary"
  
  BULLET::::- "While You Were Sleeping" (2011 TV series), a South Korean television series
  
  BULLET::::- "While You Were Sleeping" (2017 TV series), a South Korean television series
  
  BULLET::::- "While You Were Sleeping" ("The Vampire Diaries"), an episode of the TV series "The Vampire Diaries"
  
  Section::::Music.
  
  BULLET::::- "While You Were Sleeping" (album), a compilation album of Canadian rapper Classified
   Sleep inversion
  
  Sleep inversion or sleep-wake inversion is a reversal of sleeping tendencies. Individuals experiencing sleep-wake inversion exchange diurnal habits for nocturnal habits, meaning they are active at night and sleep during the day. Sleep-wake inversion, when involuntary, can be a sign of a serious disorder.
  
  Section::::Symptoms.
   BULLET::::- Falling asleep physically without losing awareness. The "Mind Awake, Body Asleep" state is widely suggested as a cause of OBEs, voluntary and otherwise. Thomas Edison used this state to tackle problems while working on his inventions. He would rest a silver dollar on his head while sitting with a metal bucket in a chair. As he drifted off, the coin would noisily fall into the bucket, restoring some of his alertness. OBE pioneer Sylvan Muldoon more simply used a forearm held perpendicular in bed as the falling object. Salvador Dalí was said to use a similar "paranoiac-critical" method to gain odd visions which inspired his paintings. Deliberately teetering between awake and asleep states is known to cause spontaneous trance episodes at the onset of sleep which are ultimately helpful when attempting to induce an OBE. By moving deeper and deeper into relaxation, one eventually encounters a "slipping" feeling if the mind is still alert. This slipping is reported to feel like leaving the physical body. Some consider progressive muscle relaxation a passive form of sensory deprivation.
   In addition to oxygen deprivation or deficiency, infections are a common pathological cause of ASC. A prime example of an infection includes meningitis. The medical website WEBMD states that meningitis is an infection that causes the coverings of the brain to swell. This particular infection occurs in children and young adults. This infection is primarily viral. Viral meningitis causes ASC and its symptoms include fevers and seizures (2010). The Impairment becomes visible the moment seizures begin to occur, this is when the patient enters the altered state of consciousness.
  
  Section::::Induction methods.:Pathologies/other.:Sleep deprivation.
   Sleep onset
  
  Sleep onset is the transition from wakefulness into sleep. Sleep onset usually transmits into non-rapid eye movement sleep (NREM sleep) but under certain circumstances (e.g. narcolepsy) it is possible to transit from wakefulness directly into rapid eye movement sleep (REM sleep).
  
  Section::::History.
   The newest version of the International Classification of Sleep Disorders (ICSD, 3rd. Ed.) uses State Dissociation as the paradigm for parasomnias. Unlike before, where wakefulness, non-rapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep were considered exclusive states, research has shown that combinations of these states are possible and thus, may result in unusual unstable states that could eventually manifest as parasomnias or as altered levels of awareness.
   Irwin pointed out that OBEs appear to occur under conditions of either very high or very low arousal. For example, Green found that three quarters of a group of 176 subjects reporting a single OBE were lying down at the time of the experience, and of these 12% considered they had been asleep when it started. By contrast, a substantial minority of her cases occurred under conditions of maximum arousal, such as a rock-climbing fall, a traffic accident, or childbirth. McCreery has suggested that this paradox may be explained by reference to the fact that sleep can supervene as a reaction to extreme stress or hyper-arousal. He proposes that OBEs under both conditions, relaxation and hyper-arousal, represent a form of "waking dream", or the intrusion of Stage 1 sleep processes into waking consciousness.
   Section::::Physiology.:Awakening.
  
  Awakening can mean the end of sleep, or simply a moment to survey the environment and readjust body position before falling back asleep. Sleepers typically awaken soon after the end of a REM phase or sometimes in the middle of REM. Internal circadian indicators, along with successful reduction of homeostatic sleep need, typically bring about awakening and the end of the sleep cycle. Awakening involves heightened electrical activation in the brain, beginning with the thalamus and spreading throughout the cortex.
   On August 6, 2008 the band announced that after 6 months of auditioning for a new pianist/guitarist to replace Cameron Keym, they had recruited Paul Cadena and Christopher Evans.
   These seizures typically initiate abruptly with either a focal or generalized onset. A prodrome (vague sense of impending seizure) may also be present before the seizure begins. The seizure itself includes both tonic and clonic contractions, with tonic contractions usually preceding clonic contractions. After these series of contractions, there is an extended postictal state where the person is unresponsive and commonly sleeping with loud snoring. There is usually pronounced confusion upon awakening.
  
  Section::::Causes.
   The unspecified type of circadian rhythm sleep disorder is characterized by a pattern of sleep-wake disturbance and circadian mismatch that is not due to the causes of the other three types. Examples of other causes include irregular sleep-wake patterns and non-24-hour sleep-wake patterns. If an individual's sleep-wake pattern is based on a period of time of slightly more than 24 hours, their circadian rhythm can become progressively delayed.
  
  Sleep inversion may be a symptom of elevated blood ammonia levels. 
  
  Section::::Diagnosis.
   Research has found a genetic component in sleep paralysis. The characteristic fragmentation of REM sleep, hypnopompic, and hypnagogic hallucinations have a heritable component in other parasomnias, which lends credence to the idea that sleep paralysis is also genetic. Twin studies have shown that if one twin of a monozygotic pair (identical twins) experiences sleep paralysis that other twin is very likely to experience it as well. The identification of a genetic component means that there is some sort of disruption of a function at the physiological level. Further studies must be conducted to determine whether there is a mistake in the signaling pathway for arousal as suggested by the first theory presented, or whether the regulation of melatonin or the neural populations themselves have been disrupted.
   Those experiencing OBEs sometimes report (among other types of immediate and spontaneous experience) a preceding and initiating lucid-dream state. In many cases, people who claim to have had an OBE report being on the verge of sleep, or being already asleep shortly before the experience. A large percentage of these cases refer to situations where the sleep was not particularly deep (due to illness, noises in other rooms, emotional stress, exhaustion from overworking, frequent re-awakening, etc.). In most of these cases subjects perceive themselves as being awake; about half of them note a feeling of sleep paralysis.
  
  Section::::Spontaneous.:Near-death experiences.
   BULLET::::1. Do you or your bed partner believe that you move your arms, legs, or body too much, or have unusual behaviors during sleep?
  
  BULLET::::2. Do you move while dreaming, as if you are simultaneously attempting to carry out the dream? l Have you ever hurt yourself or your bed partner during sleep?
  
  BULLET::::3. Do you sleepwalk or have sleep terrors with loud screaming?
  
  BULLET::::4. Do your legs feel restless or begin to twitch a lot or jump around when you are drowsy or sleepy, either at bedtime or during the day?
   Many cultural stories have been told about people falling asleep for extended periods of time. The earliest of these stories is the ancient Greek legend of Epimenides of Knossos. According to the biographer Diogenes Laërtius, Epimenides was a shepherd on the Greek island of Crete. One day, one of his sheep went missing and he went out to look for it, but became tired and fell asleep in a cave under Mount Ida. When he awoke, he continued searching for the sheep, but could not find it, so he returned to his old farm, only to discover that it was now under new ownership. He went to his hometown, but discovered that nobody there knew him. Finally, he met his younger brother, who was now an old man, and learned that he had been asleep in the cave for fifty-seven years.
   When people lose consciousness, they fall down (unless prevented from doing so) and, when in this position, effective blood flow to the brain is immediately restored, allowing the person to regain consciousness. If the person does not fall into a fully flat, supine position, and the head remains elevated above the trunk, a state similar to a seizure may result from the blood's inability to return quickly to the brain, and the neurons in the body will fire off and generally cause muscles to twitch very slightly but mostly remain very tense.
   Microsleeps sometimes are a side effect of various drugs, particularly in reference to dopamine-stimulating drugs in Parkinson's Disease. Particularly, somnolence is a recognized adverse effect of dopamine agonists, pramipexole and ropinirole. These drugs are known to cause sudden-onset sleep spells in roughly 50% of patients with Parkinson's disease (PD) while they were driving. Therefore, clinical interventions pertaining to microsleeps may also encompass reducing excessive sleepiness as a side effect of drug administration.
   Sleepiness can be dangerous when performing tasks that require constant concentration, such as driving a vehicle. When a person is sufficiently fatigued, microsleeps may be experienced. In individuals deprived of sleep, somnolence may spontaneously dissipate for short periods of time; this phenomenon is the second wind, and results from the normal cycling of the circadian rhythm interfering with the processes the body carries out to prepare itself to rest.
  
  The word "somnolence" is derived from the Latin "somnus" meaning "sleep".
  
  Section::::Causes.
  
  Section::::Causes.:Circadian rhythm disorders.
   Section::::Batini's disproving.
  
  Another research in the field of sleep, Batini, questioned Bremer's hypothesis and did an experiment similar to Bremers'. In 1939 Batini's experiment performed his experiment in which he stimulated of different areas of the reticular activating system, and his results concluded that sleep is not dependent on an influx or lack of stimulus from the body. Our bodies do not require input to have or maintain evidence of being awake.
  
  Section::::Summary.
   "A General Theory of Love" is scarcely more sympathetic to Dr. Benjamin Spock and his "monumentally influential volume" "Baby and Child Care", especially given Spock's role in promoting the movement against co-sleeping, or allowing infants to sleep in the same bed as their parents. Lewis, Amini and Lannon cite the research of sleep scientist James McKenna, which seems to suggest that the limbic regulation between sleeping parents and infants is essential to the neurological development of the latter and a major factor in preventing Sudden Infant Death Syndrome (SIDS). "The temporal unfolding of particular sleep stages and awake periods of the mother and infant become entwined...on a minute to minute basis, throughout the night, much sensory communication is occurring between them."
   Also noteworthy, is the Waterloo Unusual Sleep Experiences Questionnaire that further illustrates the correlation.
  
  Section::::Studies of OBEs.:Miss Z study.
   In another case study of a 50-year-old woman who had symptoms consistent with MCS, administration of zolpidem, a sedative hypnotic drug improved the patient's condition significantly. Without treatment, the patient showed signs of mutism, athetoid movements of the extremities, and complete dependence for all personal care. 45 minutes after 5 to 10 mg of zolpidem was administered, the patient ceased the athetoid movements, regained speaking ability, and was able to self-feed. The effect lasted 3–4 hours from which she returned to the former state. The effects were repeated on a daily basis. PET scans showed that after zolpidem was administered, there was a marked increase in blood flow to areas of the brain adjacent to or distant from damaged tissues. In this case, these areas were the ipsilateral cerebral hemispheres and the cerebellum. These areas are thought to have been inhibited by the site of injury through a GABA-mediated mechanism and the inhibition was modified by zolpidem which is a GABA agonist. The fact that zolpidem is a sedative drug that induces sleep in normal people but causes arousal in a MCS patient is paradoxical. The mechanisms to why this effect occurs is not entirely clear.
   Section::::Commercial performance.
  