Circadian Rhythms, Sleep and Dreaming

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Brain Transections Reveal Sleep Mechanisms
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The Brainstem Reticular Formation
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The Raphe Nucleus, Locus Coeruleus, and Their
Projections
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REM Sleep

• REM rapid-eye movement
• lots of brain activity - EEG shows low voltage
  fast waves
• postural muscles are most relaxed during REM
  sleep
• loose associative thinking
• PGO waves - start in the pons ? geniculate nuc of
  thalamus ? occipital cortex
• depends on the relationship between the NTs
  serotonin and acetylcholine

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Most Common Sleep Disorders

• Insomnia
• Daytime sleepiness
• Inappropriate behaviors during sleep

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Rates of sleep problems in general population
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Insomnia

• Sleep inadequate or abnormal
• Difficulty initiating sleep, frequent awakenings,
  short sleep time, non-restorative sleep
• Daytime effects - fatigue, sleepiness, impaired
  function, depression, anxiety, mood changes
• Higher rates in females, elderly, shift workers

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Insomnia - causes

• Psychiatric disorders, e.g., depression
• Chronic medical disorders, e.g., respiratory
  illness like asthma chronic obstructive lung
  disease
• Pain, e.g., duodenal ulcer
• Elderly - Periodic Leg Movements

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Nocturnal gastric acid secretion
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Restless leg syndrome
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Excessive Daytime Sleepiness

• Sleepiness is a physiological drive
• Behavioral indicators - nodding, yawning, eye
  rubbing
• Conventional 24-h sleep-waking cycle, maximal
  sleepiness occurs in the middle of the night
• Humans deprived/restricted of sleep show
  increased EEG patterns (alpha theta) while awake

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Time Required to Fall Asleep Multiple Sleep
Latency Test (MSLT)
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Baseline Drug MSLT for Caffeine Group
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Excessive Daytime Sleepiness - Causes

• Narcolepsy
• Cataplexy sudden weakness due to decreased
  muscle tone triggered by emotional event
• Hynagogic hallucinations - dreams experienced at
  sleep onset
• Sleep paralysis at sleep onset
• Obstructive sleep apnea
• Airway obstructed during sleep

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Narcolepsy in Dogs
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Neural Degeneration in Humans with Narcolepsy
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Symptoms associated with narcolepsy
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Differential Diagnosis of Narcolepsy Sleep
Apnea
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