possible template for powerpoint ... Nature of Sleep and

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Physiology of Sleep and Dreams
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Nature of Sleep and Dreams

• Sleep and dreams as biological rhythms
• When do people sleep, if they dont have a clock?
• Sleep and dreams as physiological states
• What parts of the brain are active and what parts
  are inactive during sleep and dreaming
• Sleep and dreams as drives/instincts
• What is the purpose of sleep or dreams?

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Biological Rhythms

• Circannual rhythms
• Bird migration
• Infradian rhythms
• Menstrual cycle
• Circadian rhythms
• Sleep/wakefulness cycles
• Entrainment
• Ultradian rhythms
• REM/NREM cycles

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Circadian Rhythms

• Humans, like all mammals, have a 24 hour
  biological clock
• If people are placed in an environment without
  any access to daylight, to clocks, or to other
  markers of time, they follow an activity/rest
  cycle of about 24.5 hours
• Shown by Nathaniel Kleitman in a study in Mammoth
  Cave, Kentucky

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Genetics of Biological Clocks

• Multiple genes are known to be involved in the
  clock
• per (period)
• tim (timeless)
• per and tim both have circadian rhythms
• enter nucleus at night and shut off clock
• clock
• starts production of per and tim in nucleus

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Entrainment

• A zeitgeber or timing signal, can reset the clock
• Sunrise is one signal
• Changing the time of day of the signal can alter
  the timing of the biological process

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Nathaniel Kleitman (1895-1999)

• Kleitman showed people have a biological clock
• Revolutionized study of sleep
• With Aserinsky, discovered REM sleep in 1953

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Control of Cycles

• Sleep/wake cycle and the suprachiasmatic nucleus
  (SCN)
• lesions of SCN eliminate sleep/waking cycle
• REM/NREM cycle and the pontine reticular formation

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SCN Control of Circadian Rhythm
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The Cycles of Sleep Stages
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Control of REM by Pontine Nuclei
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The Description of Brain Waves

• Two parameters
• frequency
• the number of waves per second, measured as
  Hertz, Hz
• amplitude
• the height of waves, measured in EEG recordings
  as microvolts, or ?V
• Synchronization
• synchronized waves are aligned with each other
  in time
• desynchronized waves occur randomly with each
  other in time

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Physiological Measures

• Brain waves
• Electroencephalograph (EEG)
• Beta waves 14 - 30 Hz, lt20 ?V
• Alpha waves 8 - 13 Hz, 25-100 ?V
• Theta waves 4 - 7 Hz, 20 ?V
• Delta waves .5 - 4 Hz, 20-200 ?V
• Eyemovements
• Electrooculagraph (EOG)
• Muscle tension
• Electromyograph (EMG)

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Brain Waves in Sleep

• Waking
• low amplitude, high frequency
• Stage 1
• mostly theta waves
• Stage 2
• sleep spindles
• brief period of high amp,high f
• K-complex
• Stage 3
• appearance of delta waves
• Stage 4 (slow wave sleep)
• mostly delta
• REM
• like Stage 1, but with REM

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Additional Bodily Changes

• Decreased threshold of awareness of external
  events
• Vestibular activation during REM
• Autonomic arousal in REM
• Genital arousal in REM

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Sleep Disorders

• Narcolepsy (high levels of REM)
• Hypersomnia (high levels of NREM)
• Parasomnias
• Night terrors
• Sleepwalking
• Sleeptalking
• Insomnias

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Narcolepsy

• Clinical symptoms the narcoleptic tetrad
• excessive sleepiness during the day
• cataplexy
• abrupt loss of muscle tone, without loss of
  awareness
• sleep paralysis
• muscle paralysis of sleep
• hypnagogic hallucination

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Brain Circuits in Narcolepsy
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New Ideas on Narcolepsy

• Animal models
• Doberman pinschers
• Neurochemical Basis
• Defect in Hypocretins or Orexins (HO)
• Narcoleptic people have little HO
• Genetic basis
• Defective gene found in dogs
• No genetic abnormality in people

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Evolution of Sleep

• Rest but no sleep
• amphibians, fish
• Non-REM sleep only
• lower reptiles
• A little REM
• chameleons, crocodiles, birds (when babies)
• echidna
• REM and NonREM
• All placental mammals

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Purpose of Sleep

• Excessive sleep deprivation kills rats
• Sleep deprivation makes people more tired

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Development of Sleep

• Babies spend 16 hours sleeping, initially half in
  REM
• Over lifespan, total sleep decreases
• Over lifespan, proportion of REM decreases