Brain chemical cycles cause awakeness and sleep {sleep, state}. Sleep can be unconscious or have dreaming.
causes
Monotony, warmth, and restricted movement make people sleepy. Waiting for something that cannot happen yet can make people sleepy. Regular physical exercise, good-quality firm mattress, warm but ventilated room, malted milk drink, and sexual satisfaction at bedtime promote good sleep. Deep sleep can follow epilepsy.
causes: biology
Melatonin induces sleep at night {sleep inducer} and maximizes just before morning. Neurosteroid induces sleep, can be analgesic at high concentration, and comes from cholesterol or progesterone. Sleep peptide is in brain, cerebrospinal fluid, and cerebral blood and can induce sleep.
Brain stops making monoamine neurotransmitters. Monoamine oxidase breaks down monoamines. Monoamines no longer excite motor neurons, and acetylcholines excite motor neurons. However, monoamines still go to eye-muscle nerves. When asleep, amygdala inhibits pons, which activates medial medulla, which inhibits motor neurons.
awake
When awake, forebrain inhibits amygdala, which excites pons, which inhibits locus coeruleus, which excites muscles. Monoamines block sleep by exciting motor neurons. At awakening, acetylcholine is low, and serotonin and norepinephrine are high.
brain
Arousal system, hypothalamus, locus coeruleus, raphé nuclei, and reticular nucleus affect sleep. During NREM sleep, thalamus-cortex pathways have inhibition. During REM sleep, thalamus-cortex pathways have no inhibition but receive only small input.
Pons reticular activating system has norepinephrine, serotonin, dopamine, and acetylcholine secreting neurons and has pathways to brainstem neurons. Reticular activating system neurons can inhibit afferent axons from senses and efferent axons to muscles.
animals
Higher invertebrates and chordates have rest phases. Sleep is only in vertebrates. Fish and amphibia sleep briefly or just rest. Ancient reptiles have only NREM sleep. Recent reptiles and birds have NREM sleep and some REM sleep. Mammals have NREM sleep and more REM sleep. Mammals who are more immature at birth have more REM sleep. For mammals, REM sleep is at highest percentage at birth and decreases with age. Larger mammals sleep more. In dolphins, one hemisphere NREM-sleeps for several hours, then other hemisphere NREM-sleeps, so they can continue to breathe.
Sleep is an instinct. Sleep evolved separately from dreams [Horne, 1988].
amount
In all species, sleep amount is directly proportional to waking metabolic rate. Animals with higher body temperatures, shorter reaction times, and more fat sleep longer. Birds and mammals that are not secure from predators sleep only for minutes at a time. Predators, who can sleep safely, sleep longer.
Newborns sleep 80%, with seven or eight naps per day. 12-to-18-month-old toddlers sleep 50%. Three-year-old children sleep 40%, and REM sleep is 20% of sleep. Teenagers and adults sleep 30%. Older adults have shorter and more broken sleep.
In adults, sleep amount is proportional to body weight.
purposes
Sleep causes more protein synthesis and less cellular work and so aids growth. Perhaps, sleep simplifies brain processes by removing alternative pathways. Perhaps, simple brain-activity patterns repeat and return neurons to sense and motor readiness.
A sleep-like state {animal hypnosis} can follow extreme stimulation.
People who have little sleep {sleep deprivation} cannot stay awake, have frequent small sleeps, fail to notice things, and have no attention. After little sleep, attention fails first. Little sleep for many days can cause rising temperature and then death. CX717 maintains performance after sleep deprivation. Inadequate sleep causes most fatigue.
People can get up from sleep and walk automatically {somnambulism}| {sleepwalking}. For example, children can walk half-asleep to lavatory and return to bed. Sleepwalking is an automatism and can be without consciousness [Broughton et al., 1994] [Callwood, 1990] [Jacobson et al., 1965] [Kavey et al., 1990] [Masand et al., 1995] [Moldofsky et al., 1995] [Puccetti, 1973] [Revonsuo et al., 2000] [Schenck and Mahowald, 1998] [Vgontzas and Kales, 1999]. Sleepwalking is unconscious and unaware, with no sensations.
properties
Sleepwalking lasts up to 30 minutes. Sleepwalking has purposeful movements. People can avoid obstacles and return to bed. They typically have poor coordination, are clumsy, and are unreliable. Sleepwalkers do not go anywhere unusual. Motions are smaller than normal. Eyes are open. Somnambulism can happen during orthodox sleep early at night, with large slow EEG waves, because muscle output has no inhibition. Sleepwalking occurs more in deep sleepers.
Sleepwalking can have talking. Night terror can accompany sleepwalking.
factors
Sleepwalking is more frequent with daytime anxiety.
Sleepwalking is more common among children.
Sleepwalking is hereditary.
comparisons
Sleepwalking trances are like hysterical dissociation. People look dazed, preoccupied, and unresponsive.
memory
After waking, people do not remember sleepwalking.
Dreams {dreaming} are free association narratives about self, with typical movements and surroundings [Aristotle, -350] [Cavallero and Foulkes, 1993] [Krakauer, 1990] [Louie and Wilson, 2001] [Malcolm, 1959]. Dreaming is unconscious and unaware but experiences sensations. In dreams, consciousness does not monitor cognitions.
sleep
Dreams can happen during rapid-eye-movement deep sleep [Hobson et al., 1998].
Orthodox sleep has little dreaming. Non-rapid-eye-movement-sleep dreams are mostly when first falling asleep or before waking. People remember them as well as REM-sleep dreams, but they are less interesting and have different subjects [Braun et al., 1998] [Hobson et al., 1998].
Sleep evolved separately from dreams [Horne, 1988]. Perhaps, dreams just happened when sleep evolved [Flanagan, 2000].
properties
Dreams are typically about play, recreation, and home, not current events, work, or exotic things. Dreamers are in the action, not just watching things happen. Dreams are not just watching a show. Dreams typically have strangers and friends, who are typically same age as dreamer. Family members appear less often. Both sexes appear equally. People typically change into someone else.
Almost all dreams have movements, with movement illusions. Dreams never violate arithmetic or geometry laws. Dreams have conscious episodes, each with consistent features. Episodes have no connections. However, people can distinguish one night's dreams from other-night dreams.
Dreams do not have reading, writing, or conversations between people, but may have implied conversations. People never dream rational analysis, only associations. Dreams tend to project meaning onto stimuli.
Dreams seem like movements in and through real scenes during stories, but typically have false perceptions and false beliefs, with poor memory.
One-third of dreams have color. People can always have or never have color dreams.
Complex dreams commonly have incongruity, unspecified objects, and some discontinuity. Adults and children have same proportions of discontinuity, unspecified objects, and incongruity. Adults have more complex and bizarre dreams than children do. Children's dreams are more about family and friends.
emotion
Dreaming has mostly anxiety, less frequently joy, and even less frequently anger. One-third of dreams have happy feelings. Dreams are mostly pleasant but can have anger and apprehension. Sadness, shame, and remorse are infrequent. Least common emotions are affection and eros. Erotic dreams are less than 10% of adult dreams.
Dream misperceptions can increase anxiety, and anxiety can increase misperceptions. One-third of dreams have strong anxiety and fear. Two-thirds of dreams have anxiety, fear, guilt, or sadness. As dreams continue, they get sadder. Dreams with anxiety do not have penile erections.
Dream emotion levels correlate with heart rate and skin potential. If heart beats faster and breathing rate increases, dream has anxiety. Dreams have more aggression than waking life. Emotional reactions to dream events are appropriate. Men and women have same dream emotions.
movements
Jerky eye movements, limb twitches, face twitches, middle-ear muscle twitches, and sudden respiratory changes are phasic REM-sleep components. Muscle relaxation and penile erections are tonic features. As night progresses, REM periods contain more phasic components, and dreams are more active and less passive. Limb movements relate to dreams with movement. Small face, finger, head, and limb twitches, with most other muscle activity suppressed, show dream is about running, flying, or swimming. Dreams have rapid eye movements that can follow dream movements. Large eye movements relate to dream content [LaBerge, 1985] [LaBerge, 2000]. Dreams have dilated pupils.
perception
Perception during dreaming uses same brain regions as perception during awakeness. The strongest dream perception is visual. Dream visual images are typically in color. Audition perceptions are weak. Touch, temperature, taste, and smell perceptions are very weak.
brain damage
People blind since birth have only auditory dreams. If blindness is in primary cortex, dreams have no seeing. Secondary-cortex-damage blindness allows seeing in dreams.
People are faceless in dreams of people who cannot identify faces [Kaplan-Solms and Solms, 2000] [Solms, 1997].
Patients with hemi-neglect cannot see dream right or left half.
development
20-week-old fetuses have REM sleep, indicating dreaming [Empson, 2001].
causes
Dreams are about recent events or ongoing problems. Events around sleeper during dreams often are in dreams. Human brain can respond to word meanings during sleep and have related dreams. Depressed people have dreams that contain failure and loss.
comparisons
Dreams have more characters and settings than fantasies. Unlike fantasies, dreams are not menacing and do not cause paranoia. In dreams, people often change into someone else, which never happens in fantasies.
Dreaming is like delirium, not dementia. Dreams have time and place disorientation, visual hallucinations, distractibility, attention deficit, recent memory loss, and insight loss, like hallucinations. Dreaming is like organic mental syndrome, such as caused by drugs or Alzheimer's disease.
Out-of-body experiences are similar to stage one dreaming.
behavior
Dreams do not change awake behavior [Hobson, 2002].
will
People cannot will dreams, though they can will in dreams if not in deep sleep. People cannot be responsible for dreams, so dreams cannot be sins.
interpretation
Dream-interpretation theories are invalid [Hobson, 2002] [Webster, 1995].
purposes
Perhaps, dreams help consolidate memories [Hobson, 2002] [Vertes and Eastman, 2002]. Perhaps, dreams help clear brain memory circuits and help to selectively forget [Crick and Mitchison, 1983].
Perhaps, dreams are activity rehearsals and are like playing or practice [Humphrey, 1983] [Humphrey, 1986] [Humphrey, 1992] [Humphrey, 2002].
Perhaps, dreams are rehearsals or practice against threats {threat simulation theory, dream} [Rossetti and Revonsuo, 2000] [Revonsuo, 2000].
brain
Dreams start in pons-geniculate-occipital (PGO) system, which locus-coeruleus catecholamines activate. Pons controls reticular activating system [Braun et al., 1998] [Hobson et al., 1998]. Perhaps, dreams are forebrain interpretations of midbrain signals. During dreams, brain blocks sense input.
If people are conscious or dreaming, high-amplitude electroencephalography waves arise in pons, radiate to geniculate body, and then go to occipital cortex.
Brainstem is active in REM sleep, and REM sleep has different transmitters from NREM sleep. Brainstem multiple motor-pattern generator excitations cause increased sense qualities [Empson, 2001].
Dreams have low cortex output and input, so brainstem inhibition from cortex is low. During dreams, cortex has no motor-neuron output. Area V1 and areas nearby deactivate during dreaming, while fusiform gyrus and medial temporal lobe activate. For dreams to have sense qualities, such as sight, sense primary cortex must be functioning. Removing visual cortex causes visual dreams to cease. If area V1 has damage, people can still have visual dreams.
Frontal cortex has low activity during dreaming.
Idle thinking {daydreaming}| can be conscious but unaware and experience sensations. While awake and in unchanging environments, people talk and daydream more, and then talk and daydream less, in 90-minute to 100-minute cycles. Drug frontal-lobe damage makes people have no daydreaming.
People can dream that they are waking {false awakening}. During false awakening, people can hallucinate {metachoric experience}.
As people fall asleep, they can have brief dreamlets {hypnagogic hallucination} {hypnagogic image}. Images can be vivid. Human will can control hypnagogic states [Maury, 1848].
As people wake up, they can have brief dreamlets {hypnopompic hallucination} {hypnopompic image} [Mavromatis, 1987].
Dreams have two levels, actual dream {manifest dream level} and unconscious symbolizations {latent dream level}. Perhaps, symbols are repressed wishes.
In some dreams {lucid dreaming}|, dreamers know that they are dreaming [Blackmore, 1992] [Gackenbach and LaBerge, 1988] [Green, 1968] [Hearne, 1978] [Hobson, 2002] [van Eeden, 1913]. More lucid dreaming correlates with more out-of-body experiences.
Children age 10 to 14 can have terror, shrieking, and sleepwalking {night terror}| {pavor nocturnis} in orthodox sleep early at night. Night terrors are more frequent with greater daytime anxiety. People never remember night terrors in the morning.
Scary dreams {nightmare}| are about anxieties and can happen during REM sleep, later at night. Having nightmares is hereditary.
People can have trouble sleeping {sleep, problems}. Depression has shortened sleep, with no deep non-REM sleep and earlier, longer, and more intense first REM sleep. Fever-causing peptides from bacteria increase non-REM sleep but not REM sleep.
Nighttime bed urination {bed-wetting} can happen during orthodox sleep early at night. It is more frequent with daytime anxiety.
During sleep, brain may not inhibit motor neurons {REM-sleep behavior disorder} (RBD). Pons lesions can allow movements during REM sleep.
Paralysis {sleep paralysis}| {night nurses' paralysis} can begin before REM sleep or stay after REM sleep, as well as when just falling asleep or in narcolepsy [Parker and Blackmore, 2002] [Spanos et al., 1995]. In sleep paralysis, people can be afraid, hear noises, float, or feel presences, weight on chest, touches, or vibrations [Cheyne et al., 1999] [Persinger, 1999].
Daytime sleepiness, muscle-tone loss, and/or consciousness loss {narcolepsy}| can follow laughing or stress.
Brain pathway that causes muscle-movement loss during sleep has changes. Forebrain inhibits amygdala, which excites pons, which inhibits locus coeruleus, which excites muscles. Amygdala inhibits pons, which activates medial medulla, which normally inhibits motor neurons.
Perhaps, narcolepsy is an autoimmune disorder [Guilleminault et al., 1976] [Guilleminault, 1976] [Siegel, 2000].
Narcolepsy relates to an antigen {human leukocyte antigen} (HLA).
Hypocretin peptide neurotransmitter mutations can cause mammalian narcolepsy.
In people with narcolepsis, anger, fear, laughter, anticipation, or joy can cause sudden voluntary-muscle relaxation {cataplexy}| [Wu et al., 1999]. Cataplexy maintains consciousness.
When sleeping, people go through four non-REM-sleep stages {sleep cycle}, separated by short REM-sleep periods. Sleep cycles last 90 minutes and have short dreaming stage 1, then stage 2, then stage 3, then stage 4, then stage 3, then stage 2, then dreaming stage 1, and then waking. In stage 1, heart rate and respiration rate increase, and brain is active [Dement, 1972]. Sleep gets deeper through the night. Deep sleep is greatest at 2 AM.
Awake/NREM-sleep/REM-sleep cycle has different properties at each stage {AIM model}. Sleep-cycle stages have different Activation levels, Input and output, and neurotransmitter Modulation.
activation
Activation is from pons reticular activating system and has pathways to nearby brainstem areas, thalamus, and spinal cord. Awakeness and REM sleep have high-frequency low-amplitude EEG waves. NREM sleep has low-frequency high-amplitude EEG waves. Stage II NREM sleep has distinctive sleep-spindle EEG.
Cortical regions differ in activation cycles, input, output, and modulation. Hypothalamus superchiasmatic nucleus starts NREM sleep and controls progress through NREM sleep. REM sleep activation goes from pons to lateral geniculate to occipital (PGO). Reticular formation blocks spinal-cord sense and motor activity during REM sleep [Hobson, 1989] [Hobson, 1994] [Hobson, 1999] [Hobson, 1999] [Hobson, 2002] [Hobson et al., 1998].
input and output
Reticular activating system neurons can inhibit afferent axons from senses and efferent axons to muscles. For awakeness, input comes from outside, and output goes to muscles. For NREM and REM sleep, inputs only come from inside, with no muscle output.
modulation
Modulation is by norepinephrine, serotonin, dopamine, and acetylcholine secretions from pons reticular-activating-system neuron axons. Awakeness has high norepinephrine, serotonin, and dopamine and low acetylcholine. REM sleep has low norepinephrine and low serotonin but moderate dopamine and high acetylcholine. NREM sleep has neither high nor low neurotransmitter levels.
Cholinergic axons go to amygdala and multisensory posterolateral cortex and fire when eyes move.
cycles
Sleep has four or five cycles. First cycle has long deep NREM sleep and short REM sleep. Last cycle has long REM sleep and short shallow NREM sleep.
Regular sleep {orthodox sleep} {non-rapid eye movement sleep}| {NREM sleep} {light sleep} has only small eye movements.
properties
Consciousness is not present in slow-wave sleep. NREM sleep has little dreaming but seems to have "thinking". Both REM and non-REM sleep can have talking. Words relate to thoughts or dreams.
amount
NREM sleep is 80% of human sleep.
animals
Only vertebrates have NREM sleep. Ancient reptiles have some NREM sleep. Recent reptiles and birds have NREM sleep and little REM sleep. Mammals have NREM sleep and REM sleep.
In dolphins, one hemisphere NREM-sleeps for several hours, then other hemisphere NREM-sleeps, so they can always breathe.
causes
Melatonin, which brain makes more at night, promotes NREM sleep. During NREM sleep, acetylcholine changes from low to high. During NREM sleep, serotonin and norepinephrine change from high to low.
NREM sleep releases growth hormone, decreases adrenaline and corticosteroids levels, and increases cortisol and testosterone.
Raphe-system serotonin acts on thalamus layer-five and layer-six neurons to start light sleep.
Serotonin constricts pupils.
biology
NREM sleep has low frontal cortex activity, low cortical activity, high limbic activity, and high forebrain sleep-on-cell activity.
In NREM sleep, nerve cells synchronize at low frequency.
Hypothalamus superchiasmatic nucleus starts NREM sleep and controls progress through NREM sleep.
purposes
Perhaps, non-REM sleep reduces free-radical damage.
Sleep {paradoxical sleep} {rapid eye movement sleep}| {REM sleep} {deep sleep} can have dreaming.
properties
REM sleep has limited consciousness. REM sleep has detailed dreams. Both REM and non-REM sleep can have talking. Words relate to thoughts or dreams. REM sleep completely relaxes most body muscles and stops many reflexes but has rapid eye movements. In men, REM sleep has penis erections. During REM sleep, mammals have no temperature control.
amount
Paradoxical sleep is 20% of sleep.
20-week-old fetuses have REM sleep, indicating dreaming. For mammals, REM sleep is at highest percentage at birth and decreases with age. Three-year-old children and adults sleep 20% in REM sleep.
REM sleep diminishes with anxiety.
Recent reptiles and birds have NREM sleep and little REM sleep. Mammals have NREM sleep and REM sleep. Mammals who are more immature at birth have more REM sleep.
causes
REM sleep has high acetylcholine, from brainstem, but low serotonin and norepinephrine, from sense input.
REM sleep diminishes with adenosine, barbiturate, benzodiazepines, depressants, interleukin, and sedatives.
biology
REM sleep has high limbic activity, low cortex input and output, no sense input, and no motor neuron output. REM sleep-on cells are highly active. REM sleep has faster brain blood flow than wakeful rest.
Awakening sense thresholds are highest in REM sleep, except for stage-4 sleep.
REM sleep activation goes from pons to lateral geniculate to occipital lobe (PGO).
factors
Men and women have same REM-sleep activation system and REM sleep amounts. In mental defectives, REM sleep percentage is proportional to intelligence level.
purposes
Perhaps, REM sleep is for monoamine decrease. REM sleep is probably not for readiness or memory consolidation.
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