Devices, systems and methods are disclosed for treating a variety of diseases and disorders that are primarily or at least partially driven by an imbalance in neurotransmitters in the brain, such as asthma, COPD, depression, anxiety, epilepsy, fibromyalgia, and the like. The technology involves the use of an energy source comprising magnetic and/or electrical energy that is transmitted non-invasively to, or in close proximity to, a selected nerve to temporarily stimulate, block and/or modulate the signals in the selected nerve such that neural pathways are activated to release inhibitory neurotransmitters in the patient's brain.