Deep breathing relieves stress and anxiety due to its physiological effect on the nervous system. Breathing slowly and mindfully activates the hypothalamus, connected to the pituitary gland in the brain, to send out neurohormones that inhibit stress-producing hormones and trigger a relaxation response in the body. The hypothalamus links the nervous system to the endocrine system, which secretes the hormones that regulate all activities throughout the body.
The adrenal glands, located on top of both kidneys, interact with the hypothalamus and pituitary glands. The adrenal medulla, the inner portion of the adrenal gland, secretes hormones that control how a person copes with stress. Epinephrine, also called adrenaline, and norepinephrine, called noradrenaline, secreted by the adrenal medulla, increase heart rate and blood pressure, preparing the body for the fight-or-flight response.
Fight or Flight
When under stress or anxiety, the body reacts with the fight-or-flight response. This response prepares the body for anticipated conflict or danger by propelling it into a heightened state of alertness or readiness. This natural response keeps the body out of harm's way.
Autonomic Nervous System
The autonomic nervous system consists of the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system. The sympathetic and parasympathetic nervous systems regulate how the body deals with stress. During a perceived stressful or dangerous situation, the sympathetic nervous system goes into fight or flight, triggering the adrenal glands to secrete the hormones that increase blood pressure and heart rate.
The parasympathetic nervous system works in conjunction with the sympathetic nervous system, triggering the body to secrete hormones to decrease blood pressure and heart rate, inducing a relaxation response. Breathing deeply and mindfully helps stimulate the parasympathetic nervous system to trigger this response.
Enteric Nervous System
The enteric nervous system also plays a role in how the body responds to stress. This complex system of neurotransmitters, neurons and proteins--located in the tissue of the esophagus, small intestine, colon and stomach--regulates digestive activity. Sometimes called the brain in the gut, the enteric nervous system sends messages between the digestive system and the brain, much like the central nervous system does with the body. The body experiences intestinal distress when faced with stressful situations due to the enteric nervous system. Digestive disorders such as colitis and irritable bowel syndrome stem from this system.
Breathing mindfully takes practice. When under stress, people often breathe in a shallow manner, not using full lung capacity. To breathe fully, sit up straight and place your hands on your belly, directly above your belly button. Let the fingertips of both hands touch lightly. Exhale fully through your mouth. Breathe in deeply through your nose and into your belly, so that your fingertips spread an inch apart. Let your belly fill with air. Hold your breath for two to five counts, and then exhale slowly through your nose. Match the length of the inhale with the length of the exhale. Continue breathing in this manner for five to ten minutes.