The terms chronic pain and persistent pain are often used interchangeably. Generally, pain is said to be chronic if it persists beyond the normal healing time of about three months. Chronic pain may arise from an initial injury, such as a shoulder sprain, or there may be an ongoing cause, such as illness. In many cases however, there is no clear cause. Other health problems, such as fatigue, sleep disturbance, decreased appetite, and mood changes often accompany chronic pain. Chronic pain may limit a person’s movements, which can reduce flexibility, strength, and stamina. This difficulty in carrying out everyday tasks and enjoyable activities often lead to loneliness, isolation, anxiety and depression.