In recent years, rigorous research has been conducted on entheogens, such as ayahuasca, LSD, mescaline and psilocybin, and on the empathogen Ecstasy. The goal is to evaluate their effects on addiction, cluster headaches, depression, trauma, cancer, epilepsy, death and dying, as well as to explore their value in the study of consciousness. Psilocybin - or magic mushrooms - have been used in traditional healing rituals for thousands of years. However, for more than 40 years it has been illegal in the U.S. But recent findings are tearing down the barriers surrounding psychedelic research, as it has been clinically shown that they have the ability to ease depression and soothe anxiety in patients dealing with serious illness and impending death. Two separate studies discovered that a single, moderate-to-large dose of psilocybin was able to help alleviate profound distress among cancer patients. Researchers know "how," but they do not know "why," psilocybin has worked in these settings. One theory is that psilocybin interrupts the circuitry of self-absorbed thinking that is so pronounced in depressed people, making way for a mystical experience. Neuro-imaging studies ... suggest that the positive effects of psychedelic-assisted psychotherapy are explained by changes in something in the brain called "the default mode network." It turns out that this network is hyperactive in depression. Interestingly, in both meditation and also with psilocybin this network becomes quiescent.