The Science Behind Sleep


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science of sleep, EEG, fMRI, functions of sleep, amygdala, hippocampus

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The Science Behind Sleep

  1. 1. The Adventure of Sleep Presented by: Erica Johnson [email_address] February 20th, 2009
  2. 2. The whirlwind tour… <ul><li>What, When, and How? </li></ul><ul><li>Functions of Sleep </li></ul><ul><li>Sleep & Disease </li></ul><ul><li>Sleep Deprivation </li></ul>
  3. 3. 1. What, When, and How?
  4. 4. Stages of Sleep <ul><li>1) NREM Sleep </li></ul><ul><li>Stage 1 NREM </li></ul><ul><ul><li>Stage 2 NREM </li></ul></ul><ul><ul><li>Stage 3 NREM </li></ul></ul><ul><ul><li>Stage 4 NREM </li></ul></ul><ul><li>2) REM Sleep </li></ul><ul><ul><li>Phasic </li></ul></ul><ul><ul><li>Tonic </li></ul></ul>Slow Wave Sleep (SWS)
  5. 5. Sleep Architecture: Hypnogram Sleep Cycle ~90 minutes More deep NREM (SWS) early in night, more REM later in night
  6. 6. Physiology: Brain & Body <ul><li>Polysomnography (PSG): The Gold Standard </li></ul><ul><li>1) Electroencephalogram (EEG) </li></ul><ul><li>2) Electrooculogram (EOG) </li></ul><ul><li>3) Electromyogram (EMG) </li></ul>
  7. 8. Awake EOG-L EOG-R EEG-1 EEG-2 EEG-3 EEG-4 EMG EYES: Open with blinks BRAIN WAVES: High frequency (fast) Low amplitude (small) Desynchronized MUSCLE: Strong muscle tone
  8. 9. Stage 2 NREM EOG-L EOG-R EEG-1 EEG-2 EEG-3 EEG-4 EMG EYES: Eye movements stop (slowly roll in Stage-1 NREM) BRAIN WAVES: Lower frequency (slower) Higher amplitude (larger) More synchronous Special events: K-complex and Sleep Spindles MUSCLE Lowered muscle tone
  9. 10. Stage 4 NREM (SWS) EOG-L EOG-R EEG-1 EEG-2 EEG-3 EEG-4 EMG EYES: No eye movements (contamination from EEG) BRAIN WAVES: V. low frequency (SLOW) V. high amplitude (LARGE) Synchronous brain waves MUSCLE: Lowered muscle tone
  10. 11. REM EOG-L EOG-R EEG-1 EEG-2 EEG-3 EEG-4 EMG EYES: Eyes closed…BUT Horizontal movements - back and forth BRAIN WAVES: High frequency (fast) Low amplitude (small) Desynchronized (like awake) Absent muscle tone
  11. 12. REM Sleep Paralysis All nerve connections to your skeletal body muscles are inhibited, causing paralysis
  12. 13. REM Behavior Disorder
  13. 14. Functional Anatomy
  14. 15. 2. Functions of Sleep
  15. 16. <ul><li>Brain </li></ul><ul><ul><li>Learning & Memory </li></ul></ul><ul><ul><li>Emotional Regulation </li></ul></ul><ul><ul><li>Creativity & Insight </li></ul></ul><ul><li>Body </li></ul><ul><ul><li>Immune Function </li></ul></ul><ul><ul><li>Metabolic Regulation </li></ul></ul><ul><ul><li>Restorative? </li></ul></ul>
  16. 17. Learning & Memory Consolidation <ul><li>Declarative Facts </li></ul><ul><ul><li>Episodic: SWS 1 consolidation </li></ul></ul>
  17. 18. <ul><li>Non-declarative Memory </li></ul><ul><ul><li>Procedural skills (MOTOR): Stage 2 NREM 4 </li></ul></ul>
  18. 19. 3. Sleep Disturbances & Disease
  19. 20. Circadian Rhythm & Disease <ul><li>Cognitive Deficits & Cortical Atrophy </li></ul><ul><li>Type II Diabetes </li></ul><ul><li>Obesity </li></ul><ul><li>Ulcers </li></ul><ul><li>Higher incidence of cancer </li></ul><ul><li>Hypertension & cardiovascular disease </li></ul><ul><li>Exacerbation of Psychological Pathologies </li></ul><ul><li>Reduced Sleep Efficiency </li></ul><ul><li>Death </li></ul>
  20. 21. Female Shift Workers <ul><li>Irregular menstrual cycles </li></ul><ul><li>Reduced fertility </li></ul><ul><li>Increased spontaneous abortion rate </li></ul><ul><li>Increased incidence of estrogen-receptor positive breast cancer </li></ul>
  21. 22. 4. Sleep Deprivation
  22. 23. Then & Now
  23. 24. Sleep Deprivation & Immune System <ul><li>Poorer antibody response to flu vaccine </li></ul><ul><li>Declines in Natural Killer Cell (NKC) activity </li></ul><ul><li>Implications that sleep deprivation makes one susceptible to infection </li></ul>
  24. 25. Sleep Deprivation & Metabolic Function <ul><li>Impairments in glucose metabolism (beginning signs of insulin resistance, pre-diabetic) </li></ul><ul><li>Alterations in circulating levels of hormones leptin & ghrelin </li></ul><ul><li>Higher rates of diabetes & obesity </li></ul>
  25. 26. Everson (1989) <ul><li>Flower Pot Model </li></ul><ul><li>Rats deprived of sleep 11-32 days </li></ul>
  26. 27. Severe pathology, debilitated appearance, disheveled fur, severe lesions on tails and plantar surfaces of their paws “ While the paper does not ultimate say what they think caused death, it appears to have been catastrophic immune system failure leading to septicemia.” “ Thus, rats die as quickly of sleep deprivation as they do food deprivation.”
  27. 28. The Hippocampus - Memories
  28. 30. <ul><li>New Experiences are Replayed at Sleep Onset “ Hypnagogic dreams” </li></ul>Sleep Onset – Dream Manipulation
  29. 38. The Amygdala - Emotions
  30. 40. Questions & Discussion