According to research at Harvard, anxiety has been indicated in several chronic physical illnesses, including heart disease, chronic respiratory disorders like COPD, gastrointestinal conditions such as IBS, and substance abuse. There is still a lot to learn about the way our body experiences anxiety and how it affects our physical health. However, what is certain is that long-term exposure to increased cortisol levels (i.e., anxiety) leads to decreased immunity and damage to the heart and lungs.