Reishi mushroom has been used to help enhance the immune system, reduce stress, improve sleep, and lessen fatigue. People also take reishi mushroom for health conditions such as: High blood pressure. High cholesterol. Asian literature and art have long indicated Reishi's powerful influence on spirituality. Popular Chinese folklore claims that ingesting reishi mushrooms can help the receiver attain immortality. While the plant is not psychotropic, its aforementioned properties do support mental clarity.