Question: what are the characteristics of stage 1 sleep quizlet?
Answer: Stage 1. Breathing and heart rate slow down. Pseudo-insomnia. ...  Stage 2. Out of contact with environment. Breathing and heart rate decrease. ...  Stage 3. Delta brain waves (50% or less) Breathing and heart rate decrease more. Stage 4. Delta brain waves (50% or more) Night terrors. ...  REM. When dreams occur.