Nov. 17, 2025

PSY 101      Class 35: Variations in Consciousness I (Outline)

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

Other terms:

• Unconscious 
• Unconscious
  
• Subconscious 

B. Brain Activity & Consciousness

•  electroencephalograph (EEG)

C. The role of circadian Rhythms (= Daily cycle of biological changes in humans and other animals [circa diem in Latin means "about a day"])

• Day-Night Cycle: Light => Suprachiasmatic Nucleus (SCN) => Pineal Gland => Melatonin
• Ambient temperature also affects sleep (warmer = less sleep)
  

• Jet Lag & body's biological clock: East to West (easier); West to East (harder)
  

• Melatonin: Inhibited by light; promoted by darkness

D. Sleep-Wake Cycle

Stage W: Wakefulness, awake

Stage N1: Theta waves = light sleep

Non-REM Sleep

• Stage N2: Sleep spindles & mixed EEG activity
• Stage N3: Delta (slow) waves => deep sleep
• Vague dreaming
  

REM ("Rapid Eye Movement") Sleep

• Sleep cycle at different ages
  

• Doing without Sleep: The Effects of Sleep Deprivation

• Complete

• Partial

• Selective (REM is needed!)

Why Sleep? Why REM? (We will look more deeply at these questions in the next class)

• Memory & learning (consolidation of memories) seems to require sleep
• During sleep, the brain clears itself of toxic waste products that may have built up during the day.
  

Sleep Loss and Health

• Lack of adequate sleep related to obesity, lowered immune system response
• Short and long sleepers (esp. ≤ 5 hours or ≥10 hours/night) at heightened risk of death

Insomnia = chronic problems in getting adequate sleep that result in daytime fatigue and impaired functioning

• Three forms: initiation, maintenance, early awakening

• 10% adults = serious chronic insomnia; 20-30% intermittent or mild

• Problems: productivity, elevated risk of accidents, depression, anxiety, and serious health problems

• Causes

• Treatment
  

Notes on sleeping & dreaming continue in next class.

This page was originally posted on 11/12/03