When you apply it in the evening to your lower back, behind the knees and tops of your feet, you are relaxing your sciatic nerve (the longest nerve in the body) which has a direct link to the brain (head of the nervous system). However, when you apply it to your upper body throughout the day the magnesium has a calming effect but isn't targeting that sciatic nerve. You can apply 1-2 pumps to your upper body, chest and arms anytime during the day to assist mind relaxation.