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PSYC 1000

PSYC 1000. Lecture 23. Sleep and Dreams. Circadian Rhythm Biological clock Regular bodily rhythms that occur on 24 hour (approximately) cycle wakefulness, body temperature, … “Peak” period: Evening to Morning shift with age Jet lag: bright light helps to reset biological clock Sleep

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PSYC 1000

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  1. PSYC 1000 Lecture 23

  2. Sleep and Dreams • Circadian Rhythm • Biological clock • Regular bodily rhythms that occur on 24 hour (approximately) cycle • wakefulness, body temperature, … • “Peak” period: Evening to Morning shift with age • Jet lag: bright light helps to reset biological clock • Sleep • Periodic, natural, reversible loss of consciousness • Stages of Sleep • Different forms of brain activity • REM (Rapid Eye Movement) Sleep • Recurring sleep stage, Vivid dreams • “Paradoxical sleep”: Muscles are generally relaxed, but other body systems are active

  3. Sleep and Dreams • Measuring sleep activity

  4. Brain Waves and Sleep Stages • Alpha Waves • Slow waves of a relaxed, awake brain • Delta Waves • Large, slow waves of deep sleep • Hallucinations • False sensory experiences • Hypnogogic

  5. The Sleep Cycle • Rapid eye movement (REM) • Occur at periodic intervals during sleep cycle (after stages 1-4), lasts ~ 10 minutes • Associated with dream-like mental activity • Originally called paradoxical sleep • Non-REM (NREM) • Lower levels of activity • First 4 stages of sleep cycle (~ 90 minutes) • Go through entire cycle 4-6 times, where NREM decreases and REM increases throughout night

  6. Typical Nightly Sleep Stages

  7. Why do we Sleep? • Considerable variation in duration of sleep across individuals and species • Sleep debt accumulates across 2 weeks or more of deprivation • Sleep Deprivation • Dement (1997): 80% of students sleep deprived • Many negative effects of Sleep Loss • Fatigue • Impaired Concentration • Immune Suppression • Irritability • Slowed Performance • Accidents: planes, cars and trucks, …

  8. Species Variation in Sleep

  9. Sleep Deprivation

  10. Why Do We Sleep? • There are two main functions associated with why we need sleep: • Conservation • Sleep evolved because it allowed animals to conserve energy • Restoration • NREM occurs to provide an opportunity to repair and restore brain cells • REM is necessary for normal functioning and involved in the consolidation of learning and memory

  11. Sleep Disorders • Insomnia • Chronic failure to get adequate sleep • Includes inability to fall asleep, frequent arousals during sleep, or early-morning awakening • Canadian prevalence of ~ 13% • Narcolepsy • Irresistible compulsion to sleep during daytime • Associated with cataplexy & automatic REM states • Canadian prevalence of ~ 1/2000

  12. Sleep Disorders • Night Terrors • Experience of terror and increased arousal during transition from stage 3 to 4 of sleep • Appearance of being awake but non-responsive • Most common in children • Sleep Apnea • Disorder where person stops breathing during sleep & awakes to catch their breath • Hormonal response in body kicks in when oxygen deprived • Prevalence ~ 2% of adults

  13. Sleep Disorders • Somnambulism • Sleepwalking in which people leave their beds and wander while still remaining asleep • More frequent in children (7%) than adults (2%) • Associated with NREM sleep

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