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.