When you are more on the sympathetic side, your breathing will speed up and become more shallow, your heart will beat faster, digestion/reproductive processes will slow or stop, your hands will become cold/clammy, and peripheral vision decreases, etc. All in all, your body is preparing physically to avoid the present danger. This is a very effective physiological process, when it is working as it should. Unfortunately, we often get into this state many times during our busy days from situations that are not life-threatening, but are still processed that way in our brains/bodies. When that happens several times in one day, you can feel depleted, grumpy, etc. Scientists have studied the effects of watching action-packed/frightening movies and have found that the stimulation of the movie on the brain can keep us in sympathetic dominance for several hours after the movie is over.
When you are more parasympathetic, your breathing and heart rate reset to normal, your hands/feet warm up, your body feels relaxed, less tense, and you may feel more energetic. This is a very good state to be in when you go to sleep at night, as your body will focus on healing rather than fleeing, thus resulting in a more comfortable rest.
Feeling More Relaxed
When doing somatic movements, we coordinate breathing with movement and do both slowly and with conscious awareness, almost like meditation. Somatic movements can switch the body over into the parasympathetic side of the nervous system very quickly. When I teach group classes, it is very obvious when this shift occurs. I hear sighing, yawning, stomachs gurgling. I see everyone moving slower and really enjoying the rest between movement sequences, almost treasuring the rest time as if they are content to lie there for hours, sensing the changes that they are making in their bodies. People often comment that they took the class to relieve a particular pain, but found that the most useful thing they learned was how to relax naturally. Some are so relaxed after class that they walk for awhile before driving home to enjoy the pleasant feelings they are experiencing as they walk.