Consciousness

  • States of Consciousness
    • Consciousness is awareness of our self and environment – dif levels of awareness can be induced by external factors such as drugs or internal mental efforts. Range from alertness to sleep.
    • Alertness – you’re awake
    • Daydreaming– feel more relaxed, not as focussed. Can also be light meditation (self-induced)
    • Drowsiness – just before falling asleep/after waking up. Can also be self-induced in deep meditation.
    • Sleep – not aware of world around you.4 main types (Each type oscillates at dif frequency)
      • Beta (13-30Hz) – associated with awake/concentration. Increased stress, anxiety, restlessness. Constant alertness.
      • Alpha waves (8-13 Hz) – in daydreaming. Disappear in drowsiness but reappear in deep sleep. During relaxation.
      • Theta waves (7 Hz) – Drowsiness, right after you fall asleep.
      • Delta waves (0.5-3 Hz) – Deep sleep or coma.
      • EEGs can measure brainwaves
  • Sleep Stages and Circadian Rhythms
  • Your brain goes through distinct brain patterns during sleep. 4 main stages that occur in 90 min cycles
    • (Order is from N1 -> N2 -> N3 -> N2 -> REM – Order within cycle goes How long each stage lasts depends on how long you’ve been asleep and your age)
  • First is non-rapid eye movement sleep (non-REM) – N1, N2, N3
    • N1 (Stage 1) Dominated by theta waves. Strange sensations – hypnagonic hallucinations, hearing or seeing things that aren’t there.
      • Seeing flash of light, or someone calling your name, doorbell, etc. Or the Tetris effect – if you play Tetris right before bed, you might see blocks. Also a feeling of falling – hypnic jerks. Theta waves.
    • N2 (Stage 2) – deeper stage of sleep. People in N2 are harder to awaken. We see more theta waves, as well as sleep spindles and K-complexes.
      • Sleep spindles help inhibit certain perceptions so we maintain a tranquil state during sleep. Sleep spindles in some parts of brain associated with ability to sleep through loud noises.
      • K-complexes supress cortical arousal and keep you asleep. Also help sleep-based memory consolidation. Even though they occur naturally, you can also make them occur by touching someone sleeping.
    • N3 (Stage 3) – slow wave sleep. Characterized by delta waves. Where walking/talking in sleep happens.
  • REM (rapid-eye movement) stage. Most of your other muscles are paralyzed. Most dreaming occurs during REM sleep, so paralysation inhibits actions. Most important for memory consolidation.
    • Combination of alpha, beta, and desynchronous waves, similar to beta waves seen when awake.
      • Sometimes called paradoxical sleep, because brain is active and awake but body prevents it from doing anything.
      • Waking up during REM sleep prevents memory formation of the dream.
    • Circadian Rhythms – why you get sleepy in afternoon. They’re our regular body rhythms across 24-hour period. Controlled by melatonin, produced in the pineal gland.
      • Control our body temperature, sleep cycle, etc.
      • Daylight is big queue, even artificial light.
      • Also change as you age – younger people are night owls, but older people go to bed early.
  • Dreaming
    • Everybody dreams during REM sleep. Can tell someone is dreaming because eyes are moving rapidly under eyelids, and brainwaves look like they are completely awake.
    • Activity in prefrontal cortex during REM sleep is decreased – part responsible for logic. Why things in our things that defy logic don’t seem weird.
  • Sigmund Freud
    • Dreams are our unconscious thoughts and desires that need to be interpreted. Little scientific support.
  • Evolutionary biology
    • Threat simulation, to prepare for real world.
    • Problem solving
    • No purpose
  • Other
    • Maintain brain flexibility
    • Consolidate thoughts to long-term memory, and cleaning up thoughts. People who learn + sleep retain more than those who do not sleep. But role of REM is unclear.
    • Preserve and developing neural pathways. Because infants constantly developing new neural networks spend most of time in REM sleep.
  • Dream Theories – Freud and Activation Synthesis Hypothesis
  • Do our dreams have a meaning? Sigmund Freud’s theory of dreams says dreams represent our unconscious feelings/thoughts. Like an iceberg.
    • What happens? Manifest content (Ex. Monster chasing you)
    • What is hidden meaning? Latent content (Ex. Job pushing you out)
      • Can help us resolve and identify hidden conflict.
    • Activation Synthesis Hypothesis
      • Brain gets a lot of neural impulses in brainstem, which is sometimes interpreted by the frontal cortex.
      • Brainstem = activation, and cortex = synthesis.
      • Our brain is simply trying to find meaning from random brain activity. Therefore might not have meaning.
  • Sleep Disorders
  • People with sleep deprivation might be more irritable and have poorer memory. Could be dangerous when it comes to flying airplanes or driving cars.
    • Also more susceptible to obesity – body makes more cortisol, and the hunger hormone.
    • Can also increase your risk for depression. REM sleep helps brain process emotional experiences, which can help protect against depression (not certain).
    • Can get back on track by paying back “sleep debt”
      • How much is enough sleep? 7-8 hours for adults. Varies with age and individual. Babies need a lot more.
    • More serious form – insomnia (persistent trouble falling asleep or staying asleep). Various medications but taking them too long leads to dependence and tolerance.
      • Exercising or relaxing before bed can help
    • Other end of spectrum is narcolepsy – can’t help themselves from falling asleep. Various fits of sleepiness, going into REM sleep. Can occur any time. 1 in 2000.
      • Indications it’s genetic, and linked to absence of alertness neurotransmitter.
    • Sleep apnea – 1 in 20 people. People with it are often unaware. Stop breathing while sleeping – body realizes you’re not getting enough oxygen, wake up just long enough to gasp for air and fall back asleep without realizing. Can happen 100x/night!
      • Don’t get enough N3 (slow-wave) sleep.
      • Snoring is an indication, or fatigue in morning.
    • Sleepwalking/sleep talking – mostly genetic, occur during N3 and are harmless. Occur more often in children (have more N3).
  • Breathing-Related Sleep Disorders
    • Sleeping problems can arise from brain, airways, or lungs/chest wall.
    • Obstruction to airways causes problems breathing at night
      • Air going into nose/mouth reaches the lungs. Tissues around neck may block this airflow – snoring/gasping/pauses in breathing. Called an apnea (absence of airflow).
      • Called obstructive sleep apnea, very common and gets worse as people get older.
      • People are tired/sleepy and unrefreshed when they wake up.
      • 5+ apneas an hour (measured by polysomnography)
    • In the brain, called central sleep apnea. Presence of apneas without obstruction. Problem with the control system for ventilation.
      • Cheyne-Stokes breathing (period of oscillations, then flat, etc.) pattern in polysomnography
    • In lungs or chest wall, hyperventilation can occur (high pCO2, low pO2). Caused by medication/obesity. Chronically elevated pCO2 can lead to right-sided heart failure.
  • Hypnosis and Meditation
  • Hypnotism usually involves getting person to relax and focus on breathing, and they become more susceptible to suggestion in this state – but only if they want to. More alpha waves in this stage – an awake but relaxed state.
    • Some use hypnosis to retrieve memories, very dangerous because memories are malleable. Can create false memories.
    • 2 theories for how it works:
      • Dissociation Theory – hypnotism is an extreme form of divided consciousness
      • Social Influence Theory – people do and report what’s expected of them, like actors caught up in their roles
    • Refocused attention, so sometimes it’s used to treat pain. Reduced activity in areas that process sensory input. Although it doesn’t block it out, it might inhibit attention
  • Meditation – training people to self-regulate their attention and awareness. Can be guided and focused on something in particular, like breathing, but meditation can also be unfocussed – mind wanders freely.
    • More alpha waves than normal relaxation in light meditation.
    • In deep meditation have increased theta waves in brain.
      • In people who regularly go to deep meditation, increased activity in prefrontal cortex, right hippocampus, and right anterior insula – increased attention control (goal of meditation).
    • Can be helpful for people with ADHD, or in aging.
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