Sleeping and Dreaming

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• Sleeping and Dreaming

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Electroencephalogram (EEG)

• Electrodes placed on scalp provide gross record
  of electrical activity of brain
• EEG rough index of psychological states

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EEG Waves of Wakefulness
Awake, nonattentive
1 second

• large, regular alpha waves

Awake, attentive
1 second

• fast, irregular beta waves

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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

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EEG (De)-Synchronization

• Synchronized activity
• low frequency
• high amplitude
• Desynchronized activity
• high frequency
• low amplitude

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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

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

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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

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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

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Dreams and REM Sleep

• Function??
• view today dreams dont 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

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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

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Brain Mechanisms Controlling Sleep

• Daily rhythm of sleep and arousal
• suprachiasmatic nucleus of the hypothalamus
• pineal glands secretion of melatonin
• Slow-wave sleep
• raphe nuclei of the medulla and pons
• secretion of serotonin
• REM sleep
• neurons of the pons

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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