Anxiety is a feeling of nervousness, apprehension, fear, or worry. Some fears and worries are justified, such as worry about a loved one or in anticipation of taking a quiz, test, or other examination. Problem anxiety interferes with the sufferer's ability to sleep or otherwise function. It is noteworthy that teenagers are particularly susceptible to having irritability as a symptom of a number of emotional problems, including anxiety. Anxiety may occur without a cause, or it may occur based on a real situation but may be out of proportion to what would normally be expected. Severe anxiety can have a serious impact on daily life. Anxiety disorders may be caused by environmental factors, medical factors, genetics, brain chemistry, substance abuse, or a combination of these. It is most commonly triggered by the stress in our lives. Usually anxiety is a response to outside forces, but it is possible that we make ourselves anxious with "negative self-talk" - a habit of always telling ourselves the worst will happen. Anxiety is a feeling of fear, unease, and worry. The source of these symptoms is not always known. Alternative Names: Anxiety; Feeling uptight; Stress; Tension; Jitters; Apprehension Stress is a normal feeling. In small doses, stress can help you get things done. Stress does not affect everyone the same way. Many people feel stress symptoms in their body. You may be having pain in your abdomen, headaches, and muscle tightness or pain. Medically, it has been established that chronic symptoms of anxiety and stress can crumble our body`s immune system. Irrespective of the nature of the causes of stress—real or perceived—our subconscious mind reacts with the same body response by releasing stress hormones equal to the degree of our fear, worry or sense of threat. It brings about changes in the body`s biochemical state with extra epinephrine and other adrenal steroids such as hydrocortisone in the bloodstream. It also induces increased palpitation and blood pressure in the body with mental manifestations such as anger, fear, worry or aggression. In short, stress creates anomalies in our body`s homeostasis. When the extra chemicals in our bloodstream don`t get used up or the stress situation persists, it makes our body prone to mental and physical illnesses.