No matter what I read about anxiety, it always seems to come down to stress. Prolonged stress can cause a lot of physical damage over time including producing hypertension, weight gain or loss, or circulatory problems. Stress also contributes to anxiety by causing the adrenal glands to stop functioning properly. That means you're not only under a lot of stress, but you are not physically able to handle it. When the adrenaline glands don't work properly, your moods can begin to shift radically.