Psychology: Sleep and Dreaming

Sleep, Dreaming, and Circadian Rhythms

• In the 1930s, key changes in human EEG were first noted during a night's sleep.
• In 1953, Aserinsky and Kleitman found that rapid eye movements (REM) occur beneath closed eyelids during low-voltage, fast EEG activity.
• In 1962, Berger and Oswald discovered a loss of electromyographic activity in neck muscles during the same sleep periods.

Standard Psychophysiological Measures of Sleep

• Electroencephalogram (EEG) measures electrical energy of the brain via scalp electrodes.
• Electrooculogram (EOG) measures eye movement.
• Electromyogram (EMG) measures the electrical activity of muscles.

The 5 Stages of Sleep

• The EEG of a subject during sleep is commonly divided into stages 1, 2, 3, and 4.
• When preparing to sleep, alpha waves (8 to 12 Hz) begin to punctuate the low-amplitude, high-frequency EEG of active wakefulness.
• Stage 1 sleep features a low-amplitude, high-frequency signal, similiar to active wakefulness but slower.
• Sleep spindles, 1-2 second waxing and waning bursts of 12 to 14 Hz waves, are present.
• A K complex is present-- a single large negative wave followed by a single large positive wave.

Sleep progression

• Amplitude of EEG waves increases and frequency slows as sleep continues.
• It is customarily divided into 3 stages: stages 2,3 and 4.
• Stage 1 is the transition between wakefulness and sleep and is characterized by theta waves.
• Stage 3 has occasional delta waves (1-2 Hz), the largest and slowest EEG waves and is the transition between light and very deep sleep with deep, slow brain waves known as delta waves begins to appear.
• Stage is also known as delta sleep due to the predominance of delta waves and lasts approximately 30 minutes.
• Body temperature decreases and heart rate slows in stage 2, which lasts about 20 minutes.

Stage 5 (REM) Sleep Characteristics

• Rapid eye movements, loss of core muscle tone, and emergent stage 1 occur
• Cerebral activity (oxygen consumption, blood flow, neural firing) increases to near-waking levels.
• Autonomic nervous system activity (blood pressure, pulse, respiration) also increases.
• Muscles of extremities occasionally twitch, and some degree of penile and clitoral erection.

REM Sleep and Dreaming

• High correlation between REM sleep and dream recall is present
• External stimuli can be incorporated into dreams.
• Dreams do no last only an instant.
• Some people do not dream.
• Penile erections do not indicate dreams of sexual content.
• Sleep talking or sleep walking do not occur during sleep.

Further facts about sleep states

• Emergent sleep 1, or paradoxical sleep, has EEG and automatic activities that are similar to wakefulness.
• Sleep cycles take about 90 minutes each, with 4 or 5 cycles per night.
• After the first cycle of sleep EEG, the night involves transitioning back and forth thru the stages.

Theories of dreaming

• Sigmund Freud theorized dreams are triggered by unacceptable repressed wishes and are "the royal road to the unconscious."
• Activation-synthesis theory, developed by J. Allan Hobson and Robert McCarley (1977): Physiological brain processes cause dreams, Circuits in the brain stem are activated during REM sleep. Areas of the limbic system (emotions, sensations, memories) become active including the amygdala and hippocampus and synthesize and interpret internal activity, attempting to create meaning which results in dreaming.
• While reliant on physiological processes, dreams are not meaningless. Dreams = a conscious state allowing recombination of cogntivie elements + new ideas.
• Although most may be nonsense if novel ideas are useful then dream time is not wasted.
• Lucid dreams refer to the knowledge that the one one os dreaming, and he courses one takes can influence the dream.

Why Do We Sleep?

• Recuperation Theory: Being awake disrupts body homeostasis, and sleep restores it.
• Circadian Theory: Sleep evolved to keep animals inactive when they don't need to be engaging in activities necessary for survival.

Circadian Rhythm

• Circadian Rhythm is the diurnal or daily cycles of body function and the sleep-wake cycle.
• Zeitgebers, or "time-givers", are environmental cues that control the timing of circadian rhythms (ex: light-dark cycle).
• The Suprachiasmatic Nucleus (SCN) is responsible for the control center of circadian rhythms.
• The SCN regulates waking/sleeping by controlling levels of activity in brain which has control levels of the pineal gland and the hormone melatonin.
• Biochemistry starts melatonin secretion increase 2-3 hours before bedtime and is also use to reset the biological clock through is effect on on receptors of the SCN.

Circadian Sleep Cycles Disruption

• Jet Lag occurs when zeitgebers are accelerated during eastern flights (phase advances) or decelerated during western flights (phase delays).
• Shift Work occurs when the zeitgebers stay the same but workers adjust their sleep-wake cycles to changing work schedules.

Effects of Sleep Deprivation

• Recuperation Theory says: Long wakefulness causes physiological and behavioral disturbances which worsen as deprivation continues, and much missed seep will be regained post-deprivation.
• Circadian Theory says: There are no debilitating effects of sleep deprivation other than the desire to sleep greater during normal sleeping phases, with little compensation for lost sleep after deprivation ends.

Drugs That Affect Sleep

• Hypnotic Drugs increase drowsiness, decrease time to fall asleep, reduce awakenings, and increase total sleep time and example, benzodiazepines (Valium, Librium).
• Antihypnotic Drugs reduce sleep, may be stimulants (cocaine, amphetamine, caffeine), tricyclic antidepressants, may suppress REM, are often addictive.

Sleep Disorders

• Many disorders fall into 2 categories. Dyssomnia is disturbances in amount/quality/timing of sleep (insomnia, hypersomnia, narcolepsy)
• Parasomnia is unnatural/abnormal behaviors, emotions, perceptions during sleep (somnambulism, nightmares, sleep terrors).
• Insomnia is the difficulty initiating or maintaining sleep.
• Hypersomnolence is excessive sleepiness with difficulty feeling refreshment.
• Narcolepsy is repeated, brief, irresistible daytime sleep attacks.

Additional Sleep Disorders

• Sleep Apnea causes repeatedly disturbed sleep due to interruptions of breathing.
• Restless Legs causes tension or uneasiness tht keeps a person from falling asleep.
• Sleep State Misperception is mistaking sleep for wakefulness.
• Somnambulism is sleep walking.
• REM behavior disorder is violent and vigorous body movements during REM sleep.
• Night Terrors are extreme anxiety during seep in which one awakens screaming for an unknown terror.

Other Sleep Disorders

• Periodic limb movement disorder is the repeated involuntary movement of arms and legs, especially when falling asleep.
• Bruxism is teeth-grinding during sleep.
• Sexomnia is sexual acts while asleep with not rememberance.

Explore the fascinating world of sleep, dreaming, and circadian rhythms. Learn about the key changes in human EEG during sleep, the discovery of rapid eye movements (REM), and the loss of electromyographic activity in neck muscles during sleep periods. Delve into the standard psychophysiological measures of sleep, including EEG, EOG, and EMG, and discover the five stages of sleep.