what are the characteristics of stage 1 sleep quizlet?
['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.']