Sleeping

Sleeping Consists of Four Stages:


 

Stage 1: During stage one, the person can still be easily woken up. She encounters brief vivid images, called hypnagogic imagery. 


Stage 2: Rapid brain wave activity, called sleep spindles, begin to occur. The body temperature and the heart rate slow down.

Stage 3 and 4 (slow-wave sleep): characterized by large delta waves that come in 4 waves per second. It is very hard to wake up a person in this stage.

REM sleep: During REM sleep, the heart rate increases, the muscles become paralyzed, and the eyes begin to move rapidly. REM sleep occurs every 90 minutes for about five to thirty minutes.

 

 

Brain Waves

Four types of brain waves cycle through our brains: delta, theta, alpha and beta. These four brain waves are called the electroencephalogram (EEG).


Beta waves occur when a person is thinking hard or is mentally concentrating on a specific topic. 


Alpha waves occur when we are relaxed but awake. 


Theta waves occur during the first stage of sleep. 


Delta waves are the slowest and they occurs during slow-wave sleep.