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Sleep

Swetha Rao. Sleep. Why is sleep important?. We sleep for nearly 1/3 of our lives Concentration, Memory, and Coordination Sleep Loss = Alcohol

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Sleep

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  1. Swetha Rao Sleep

  2. Why is sleep important? • We sleep for nearly 1/3 of our lives • Concentration, Memory, and Coordination • Sleep Loss = Alcohol • Lack of sleep can increase risk of diabetes, cardiovascular disease and heart attacks, stroke, depression, high blood pressure, obesity, and infections • Sleep Disorders affect up to 70 million people

  3. Slow Wave Sleep • First hour or so brain waves slow down • relaxation of the muscles and the eyes • Heart rate, blood pressure, and body temperature all fall • If awakened, most people recall only fragmented thoughts, not an active dream

  4. REM Sleep • Rapid Eye Movement • Next half hour or so, neocortical EEG waves become similar to waking • Atonia: paralysisof the body’s muscles (only the muscles that allow breathing and control eye movements remain active) • Active dreaming • Heart rate, blood pressure, and body temperature become much more variable • Men often have erections • First REM period usually lasts 10 to 15 minutes.

  5. Stages of Sleep

  6. Insomnia • Initially or partway awakening • Short-acting sedatives and sedating antidepressant drugs suppress deeper stages of slow wave sleep

  7. Obstructive Sleep Apnea • Deeper sleep = Airway muscles collapse and close airway • Can’t enter deeper stages of slow wave sleep • High blood pressure, increased risk of heart attack, increased risk of automobile accidents, • Treatments to reduce airway collapse: lose weight, avoid alcohol and sedating drugs, avoid sleeping on back • Devices that induce continuous positive airway pressure

  8. Muscles fail to become paralyzed • Periodic Limb Movements • Intermittent jerks of legs and arms as entering slow wave sleep • REM Behavioral Disorder • Muscles fail to become paralyzed • Act out dreams • Common in Parkinson’s patients • Treated with: benzodiazepine (clonazepam)

  9. Narcolepsy • Switching mechanisms don’t work properly • Loss of nerve cells in the lateral hypothalamus which contains the neurotransmitter orexin • Narcoleptic Dog: http://www.youtube.com/watch?v=X0h2nleWTwI

  10. Sudden Sleep Attacks during the day • Hypnagogic Hallucination: Enter REM sleep and dreaming state while still partially awake • Cataplexy: Attacks of paralysis triggered by emotional experience

  11. Sleep Regulation: AWAKE • Acetylcholine and Monoamines (norepinephrine, serotonin, dopamine, and histamine)

  12. REM sleep: • Cholinergic nerve cells send signals to activate the thalamus • EEG similar to wakefulness • Monoamine pathway is quiet • Perceived as a dream

  13. Waking Up • Two groups of nerve cells in hypothalamus • Ventrolateralpreoptic nucleus: • GABA and galanin • When they fire, they turn off arousal system and cause sleep • Damage = irreversible insomnia • Neurotransmitter orexin: • Excitatory signal to monoamine neurons • Orexin levels in patients with narcolepsy are abnormally low

  14. Need for Sleep: Homeostasis • Body’s need to seek a natural equilibrium • Adenosine (chemical) • increases in the brain during prolonged wakefulness • levels modulate homeostasis • Caffeine acts as an adenosine blocker

  15. Circadian Timing System • Suprachiasmatic nucleus: group of nerve cells in hypothalamus that acts as a master clock • Cells express clock proteins which go through biochemical cycle of 24 hrs • Receives input from retina so can be reset by light

  16. Suprachiasmatic nucleus • Subparaventricular nucleus • Dorsomedial nucleus of hypothalamas • Ventrolateralproptic nucleus (orexin) • Regulate sleep and arousal

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