Anxiety is a normal reaction to stress, and in moderation, can help to improve performance [1158]. Anxiety can become problematic however, when the fear or worry is excessive, or a person has difficulty controlling their worry, and/or repetitive intrusive thoughts or actions. Symptoms of anxiety include poor concentration, an inability to relax, sleep disturbances, depersonalisation, and physical symptoms such as dizziness, faintness, headaches, nausea, indigestion, loss of sexual pleasure, breathing difficulties, sweating, tension and muscle pain, and heart palpitations.