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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:

B. Brain Activity & Consciousness

[EEG Diagram][Type of Brain Waves]

C. Biological Rhythms & Sleep

D. Sleep-Wake Cycle

Stages W (Wakefulness), N1, N2, N3 & REM ("Rapid Eye Movement") NOTE THIS IS NEW & DIFFERENT FROM THE BOOK (Silber et al, 2007)

[Stages of Sleep - New
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)


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