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The Biology of Sleep

The Biology of Sleep. How Do We Research Sleep?. EEGs Monitor brain waves Wake people up in the midst of a sleep cycle or dream Eugene Aserinsky – discovered REM sleep Works with Nathaniel Kleitman William Dement – Father of sleep medicine; World’s first sleep laboratory. Body Rhythms .

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The Biology of Sleep

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  1. The Biology of Sleep

  2. How Do We Research Sleep? • EEGs • Monitor brain waves • Wake people up in the midst of a sleep cycle or dream • Eugene Aserinsky – discovered REM sleep • Works with Nathaniel Kleitman • William Dement – Father of sleep medicine; World’s first sleep laboratory

  3. Body Rhythms • Circadian Rhythms (about a day) • Body rhythms that occur on a 24 hour cycle • Biological clock • Sleep-Awake cycle • Ultradian Rhythms • Occur more than once a day • Sleep stages

  4. Sleep and the Brain • Suprachiasmatic Nucleus (SCN) • Cluster of neurons in the hypothalamus • Receives info about day and night cycles from the retina • Depending on cycles detected by eye, it releases neurotransmitters that control body temperature, metabolism, blood pressure, hormone levels, hunger • Works with pineal gland • Adenosine • Chemical that triggers sleepiness (high levels = sleepiness) • Melatonin • Levels rise as it gets darker (makes us ready for sleep!)

  5. Other Brain Parts and Sleep • Pons: Involved in REM sleep • Sends signals to shut off spinal cord • Thalamus: helps us tune out sensory signals during sleep

  6. Other Facts About Sleep… • Bright light at night delays sleep • Thinking is sharpest and memory is most accurate when we are at our daily circadian peak • After pulling an all nighter you may get a second wind after your normal wake-up time arrives

  7. Sleep Stages (Every 90 minutes) • Awake/Relaxed • Alpha waves: slow brain waves • Beta waves are alert, waking waves

  8. Stage 1-2: Light Sleep • Stage 1: • Irregular brain waves • Slowed breathing • Hypnagogic Sensations: • Similar to hallucinations • Floating weightlessly, falling, etc • Stage 2 (after 10-15 minutes): • Sleep spindles – bursts of rapid, rhythmic brain wave activity • Could be awakened without too much difficulty • Spend 50% of the night here Sleep talking usually occurs in these stages!

  9. Stage 3-4: Deep Sleep • Stage 3: • Delta waves: large, slow waves • Stage 4: • More delta waves • Deep sleep • Hard to waken you during these stages (disoriented) • Sleep walking usually occurs here

  10. REM – Rapid Eye Movement • Heart rate rises, breathing becomes rapid and irregular, eyes dart around • Brainwaves resemble waking brain waves • However, brainstem blocks the messages from the motor cortex (although it is active) • Paradoxical Sleep • 20% of the night is spent here

  11. Cycle Repeats About Every 90 Minutes • With each 90-minute cycle, stage 4 sleep decreases and the duration of REM sleep increases

  12. Why Do We Need Sleep? • Sleep protects • A species sleep patterns suits its ecological niche • Animals with the greatest need to graze and the least ability to hide tend to sleep less • Helps us recuperate, restore, and repair brain tissue • Helps us restore and rebuild our fading memories • Helps creativity • May play a role in the growth process (pituitary gland releases growth hormone)

  13. Sleep Disorders • Insomnia • Apnea • Nightmares v Night terrors • Narcolepsy

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