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Sleeping and Dreaming

Explore the stages of sleep, EEG waves, functions of sleep, REM sleep characteristics, and common sleep disorders. Learn how sleep deprivation affects performance and the importance of circadian rhythm. Discover the brain mechanisms controlling sleep.

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Sleeping and Dreaming

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  1. Sleeping and Dreaming

  2. Electroencephalogram (EEG) • Electrodes placed on scalp provide gross record of electrical activity of brain • EEG :rough index of psychological states

  3. EEG Waves of Wakefulness Awake, nonattentive 1 second • large, regular alpha waves Awake, attentive 1 second • fast, irregular beta waves

  4. 1 second Sleep stage 1 Sleep stage 2 Spindlers (bursts of activity) Sleep stage 4 Delta waves Stages of Sleep • Stage 1 - brief transition stage when first falling asleep • Stages 2 - 4 (slow-wave sleep) - successively deeper stages of sleep • Characterized by increasing percentage of slow, irregular, high-amplitude delta waves

  5. EEG (De)-Synchronization • Synchronized activity: • low frequency • high amplitude • Desynchronized activity: • high frequency • low amplitude

  6. REM sleep (paradoxical sleep) Characteristics EEG waves-irregular, low-amplitude, high frequency waves (like beta waves) Postural muscle paralysis Rapid Eye Movements genital arousal irregular heart rate, blood pressure, breathing Dreams

  7. Sleep during a typical night • 4- 5 cycles; Duration :About 90 minutes • REM sleep takes up increasing amounts of cycle as night progresses

  8. Functions of Sleep • Restoration theory • Preservation and protection theory - sleep emerged in evolution to preserve energy and protect during the time of day when there is little value and considerable danger

  9. Sleep Deprivation • Has little effect on performance of tasks requiring physical skill or intellectual judgment • Hurts performance on simple, boring tasks more than challenging ones • Most reliable effect is sleepiness itself

  10. Dreams and REM Sleep • Everyone dreams several times a night • true dream - vivid, detailed dreams consisting of sensory and motor sensations experienced during REM • sleep thought - lacks vivid sensory and motor sensations, is more similar to daytime thinking, and occurs during slow-wave sleep

  11. Dreams and REM Sleep • Function?? • view today : dreams don’t serve any purpose, but are side effects of REM • Purpose of REM? • to exercise groups of neurons during sleep? • some are in perceptual and motor areas • REM rebound: shows significance of REM • REM occurs in other mammals • More REM in fetuses and infants • REM sleep may help consolidate memories

  12. Circadian Rhythm • Any rhythmic change that continues at close to a 24-hour cycle in the absence of 24-hour cues • body temperature • cortisol secretion • sleep and wakefulness • No time cues: cycle becomes longer than 24 hours

  13. Brain Mechanisms Controlling Sleep • Daily rhythm of sleep and arousal • suprachiasmatic nucleus of the hypothalamus • pineal gland’s secretion of melatonin • Slow-wave sleep • raphe nuclei of the medulla and pons • secretion of serotonin • REM sleep • neurons of the pons

  14. Sleep Disorders • Somnambulism - sleepwalking • Nightmares - frightening dreams that wake a sleeper from REM • Night terrors - sudden arousal from sleep and intense fear accompanied by physiological reactions (e.g., rapid heart rate, perspiration) that occur during slow-wave sleep • Narcolepsy - overpowering urge to fall asleep that may occur while talking or standing up • Sleep apnea - failure to breathe when asleep

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