|PSY 101 Variations in Consciousness I|
Consciousness and Sleep
Have you ever been "unconscious" because of an accident or anesthesia? What happened? What was it like?
A. Consciousness = awareness of internal & external stimuli
- Awareness of external events now
- Awareness of internal sensations now
- Awareness of self as an individual having these experiences
- Awareness of having thoughts about these experiences
- Unconscious (noun; psychoanalytic term of Freud) = Not accessible to consciousness (e.g.,"The unconscious contains my forgotten wishes")
- Unconscious (adjective) = in a coma, e.g. due to a head injury (e.g., "He was in a car accident and is unconscious in the intensive care unit") or the result of anesthesia in a hospital
- Subconscious (noun) = not currently part of consciousness (e.g., "I wasn't aware of the smell of the chocolate, but my subconscious probably was and prompted me to buy a bag of M&Ms")
B. Brain Activity & Consciousness
- Arises from a distributed network of neural pathways (though damage to the brain stem will impair consciousness)
- Measurement of brain activity by electroencephalograph (EEG)
C. Biological Rhythms & Sleep
- Circadian Rhythms = Daily cycle of biological changes in humans and other animals (circa diem in Latin means "about a day")
- Alertness (Adolescents = tends to be after 10 am!)
- Body Temperature (low at night; high in afternoon)
- Growth Hormone secretions (during sleep)
- Day-Night Cycle: Light sent to the Suprachiasmatic Nucleus (SCN) which affect the => Pineal Gland (pineal = "like a pine cone") which normally secretes => Melatonin
- Light has the effect of resetting the day-night cycle
- Ambient (surrounding) temperature also tends to be important in promoting sleep. If the ambient temperature is high, it is more difficult for an individual to fall asleep.
- Jet Lag & body's biological clock: East to West (easier); West to East (harder)
- Inhibited by light; promoted by darkness
- Highest level during the night
- Promotes drowsiness
- Can help individuals who experience jet lag by resetting their biological clocks.
D. Sleep-Wake Cycle
- Measurement by electromyograph (EMG; muscles); electrooculograph (EOG; eye movements); electrocardiograph (EKG; heart)
Stages W (Wakefulness), N1, N2, N3 & REM ("Rapid Eye Movement") NOTE THIS IS NEW & DIFFERENT FROM THE BOOK (Silber et al, 2007)
Stage W: Wakefulness/awake
Stage N1: Theta waves = light sleep
Stage N2: Sleep spindles & mixed EEG activity
Stages N3 Delta (slow) waves => deep sleep
REM ("Rapid Eye Movement") Sleep
- High frequency waves; discovered in 1950s
- Associated with dreaming
- Hard to awaken
- Relaxed muscles (almost paralyzed; no movement of arms and legs)
- Differences in sleep over life
- Infants: much sleep more more & high amounts of REM sleep (50%->30% over first year)
- Adults: REM steady at ca. 20% & less deep sleep needed in old age
- Deprivation: Complete (tends not to be harmful), partial (dangerous due to motor & safety problems), selective (REM is needed!)
- Adolescent Sleep Patterns (2006 National Sleep Foundation Study)
- Recommended = 9 hours
- Actual Average =
- 7.2 hours (African American)
- 7.6 hours (Hispanic)
- 7.7 (White non-Hispanic)
- 6.9 hours among 12th graders.
- 28% fall asleep in school; 22% fall asleep doing homework; 51% have driven while drowsy in last year (15% drive drowsy once a week).
- Insomnia: 15% of adults = severe; 15% = mild or occasional
- Causes: stress, tension, some health problems, use of stimulants (caffeine and others)
- Treatment: Use of sedatives (short term); change the underlying causes (long term)
Gradisar, M., Gardiner, G., & Dohnt, H. (2011). Recent worldwide sleep patterns and problems during adolescence: A review and meta-analysis of age, region, and sleep. Sleep Medicine, 12, 110-118.
National Sleep Foundation (2006). 2006 Sleep in America poll. Washington, DC: WBA Market Research.
Silber, M. H., Ancoli-Israel, S., Bonnet, M. H. et al. (2007). The visual scoring of sleep in adults. Journal of Clinical Sleep Medicine, 3(2), 121-131.
This page was originally posted on 11/12/03 and last updated on November 15, 2016