PSYC 1020H Chapter Notes - Chapter 5: Jet Lag, Circadian Rhythm, Non-Rapid Eye Movement Sleep
3 May 2018
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Variations In Consciousness
The Nature of Consciousness
● Consciousness is the continually changing stream of mental activity. There is
some degree of awareness during sleep and sometimes even when patients are
under anesthesia.
● Consciousness clearly is adaptive, but the question of exactly why it evolved is
open it debate. Variations in consciousness are related to brain activity, as
measured by the EEG.
Biological Rhythms and Sleep
● The cycle of sleep and wakefulness is influenced by circadian rhythms. Exposure
to light resets biological clocks by affecting the activity of the suprachiasmatic
nucleus and the pineal gland, which secretes melatonin.
● Being out of sync with circadian rhythms is one reason for jet lag and for the
unpleasant nature of rotating shift work. Melatonin may have some value in
treating jet lag and other sleep problems, but more research is needed.
The Sleep and Wake Cycle
● During a night’s sleep, you evolve through a series of stages in cycle of
approximately 90 mins. During the REM stage, you experience rapid eye
movements, brain waves characteristic of waking thought, and vivid dreaming.
The sleep cycle tends to be repeated four times in a night, as REM sleep
gradually becomes more predominantly and NREM sleep dwindles.
● The REM portion of sleep declines during childhood, levelling off at around 20 %.
During adulthood, slow-wave sleep decline. Culture appears to have little impact
on the physiological experience of sleep, but it does influence sleeping
arrangements and napping patterns.
● People often underestimate the impact of sleep deprivation. Going without sleep
appears to contribute to many transportation accidents and mishaps at work.
Research of selective sleep deprivation suggests that people need REM sleep
and slow-wave sleep.
● Many people are troubled by sleep disorders. Foremost among these disorders is
insomnia, which has a variety of causes. Other common sleep problems include
narcolepsy, sleep apnea, night terrors, nightmares, and somnambulism.
Document Summary
Consciousness is the continually changing stream of mental activity. There is some degree of awareness during sleep and sometimes even when patients are under anesthesia. Consciousness clearly is adaptive, but the question of exactly why it evolved is open it debate. Variations in consciousness are related to brain activity, as measured by the eeg. The cycle of sleep and wakefulness is influenced by circadian rhythms. Exposure to light resets biological clocks by affecting the activity of the suprachiasmatic nucleus and the pineal gland, which secretes melatonin. Being out of sync with circadian rhythms is one reason for jet lag and for the unpleasant nature of rotating shift work. Melatonin may have some value in treating jet lag and other sleep problems, but more research is needed. During a night"s sleep, you evolve through a series of stages in cycle of approximately 90 mins.
