Sleep: Altered Consciousness
3 standard psychophysiological measures of sleep:
EEG – Electroencephalography
Electrical activity in the brain
EOG – Electrooculography
Measures eye movements
EMG – Electromyaphography
EEG stages of sleep:
Relaxed wakefulness: Alpha waves. Low amplitude, high frequency waves. 8-12Hz
Stage 1: Theta waves. High amplitude, low frequency.
Stage 2: Sleep spindles, K-complex. Spindles: High amplitude, high frequency (12-14Hz). K-
Complex: Very high amplitude, low frequency.
Stages 3 and 4: Delta Waves. Low frequency, high amplitude (1-2Hz)
REM or dreaming sleep: Beta waves and theta waves. High frequency, low amplitude.
Children: More deep sleep stages.
Young adults: A combination of stages ¾ and stages ½.
Elderly: Very rarely in stages ¾. Wake up more often during the night.
Sigmund Freud (1856-1939): Dreams are symbolic representations of repressed sexual conflict.
The dream’s latent content (desires) expressed symbolically in its manifest content (plot). No
convincing evidence of all this.
Allan Hobson (1989): Activation Synthesis Hypotheses: Dreams reflect random activity of
cerebral circuits during REM sleep. These random neural firings produce fragmentary images
that our brains make sense of by creating stories. According to this view, dreams are deeplypersonal and reflect the particular information, capacities and tendencies already stores in our
REM Dream Content:
Often about daily lives: traces of day’s experiences, concerns. Sensory stimuli of sleeping
Report: 80% involve negative emotions
SLS Dream content
Less vivid, situation rather than stories.
Most people report dreaming when awakened during REM sleep.
REM Sleep first noted by Aristotle.
Physiological correlates of REM sleep
Rapid eye movements
Lack of core muscle tone – paralysis
Cerebral activity increases
Autonomic nervous system activity increases
Drugs that inhibit serotonin secreting neurons cause visual hallucinations.
Slow Wave Sleep: Basal forebrain region (includes preoptic area): Electrical stimulations causes
cats to fall asleep. Bilateral lesions in cats produces a substantial reduction of sleep time.
REM – Caudal reticular formation
Comparative studies of sleep
virtually all animals sleep
Reptiles, amphibians, fish and insects have cycles of inactivity
Birds, have short NREM and REM (9 seconds)
Reptiles have no REM
Why do we sleep? 1) Recuperative theory: sleep repairs the wear and tear done to our bodies while awake
2) Circadian theories: Sleep evolved to encourage inactivity during unproductive and
dangerous parts of the day
Effects of sleep deprivation: No change in performanc