What are the states of consciousness?

Although we think of our mind as awake and asleep, there are actually three states of consciousness: Wakefulness, NREM (non-rapid eye movement) and REM (rapid eye movement) Sleep (Please see learn about your sleep). The three types of sleep are very different from each other. Table 1 summarizes the differences.

Table 1. Characteristics of the 3 Brain States

Wakefulness NREM Sleep REM Sleep
Eye Movements
Present
Slow
Rapid
Alertness
Alert and aware of environment
Not alert or aware of environment
Brain activity
Active
Not active
Active
Dreams
None
None
Present
Motor Activity
Able to move
Muscles relaxed, no movement
Muscles are paralyzed (twitches can be seen)
BP, HR, Respiration, Body Temperature Regulation
Changes based on activity
Body is at rest and all are reduced.
Variability is present. Body is poikilothermic*
Summary
You are awake, able to move and respond to environment. “Active mind in an active body.”
You are asleep; brain and body are quiet and resting. “Quiet mind in a quiet body.”
You are asleep; brain is active and muscles are paralyzed. “Active mind in a paralyzed body.”

*absence of body temperature regulation