AP Psychology Ch.4: Stages of Sleep

REM (Rapid Eye Movement) Sleep

An active type of sleep where most of a person's dreams occurr. Voluntary muscles are inhibited which causes very little movement.

Non-REM Stage Two: Sleep Spindles

As people drift further into sleep, body temperature continues to drop, heart rate slows down, breathing becomes more shallow and irregular and the EEG will show sleep swindles. This is brief bursts of lasting only a second or two. Theta waves are still present but when people awake in this stage they know that they were sleeping.

Non-REM Stage 1: Light Sleep

As theta waves increase, they enter this stage. When people wake up at this point they believe that they didn't even fall asleep. They will also experience Hypnagogic images which are bits and pieces of what may become dreams, but are seen as flashes of light. Many researchers have explained that the extraterrestrial activity of ghosts aliens and etc are most explained by these images. Another occurrence is called hyping jerk which is more common because it is when the body jerks while sleeping.

Non-REM Stage Three and Stage Four: Delta Waves Roll In

Delta waves make their appearance in this stage, being the slowest and largest waves. These wave make up 20 to 50 percent of the brain wave pattern. Once the delta waves account for more than 50 percent of the brain activity, the person has entered the stage 4 of sleep. During this stage growth hormones are released from the pituitary gland and reach their peak. Therefore the body is at its lowest level of functioning. People in deep sleep are very hard to awaken. More sleep disorders are more common in young boys than young girls because boys sleep more deeply than girls due to high levels of male hormone testosterone.

Non-REM Sleep

Much deeper and more restful kind of sleep. The body is more free and likely to move around.