In psycho-aromatherapy, essential oils are used to either stimulate or relax the brain. Some oils can have calming and tranquilizing effects; others are energizing and can help relieve depression. These oils can relief stress and anxiety and promote a general feeling of well-being. In therapeutic aromatherapy, essential oils treat medical conditions. For example, they can fight infections, promote wound healing, reduce inflammation, affect hormonal levels, stimulate the immune system, heat the skin in a liniment, promote blood circulation and digestion, and lessen sinus or lung congestion.