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Sleeping and Dreaming

Sleeping and Dreaming. Electroencephalogram (EEG). Electrodes placed on scalp provide gross record of electrical activity of brain EEG :rough index of psychological states. EEG Waves of Wakefulness. Awake, nonattentive. 1 second. large, regular alpha waves. Awake, attentive. 1 second.

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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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