Anxiety and depression each affects ~15% of New Zealanders. They and other neurotic and stress-related disorders (where patients focus on negative emotional states) are a leading cause of health disability, with high chronicity, severity, costs to public health, and suicide risk. Conventional drugs often target only some of these disorders, taking months for their full effects. Thirty percent of patients are completely treatment resistant, with high use of public resources and risk of suicide attempts; but ketamine appears swiftly therapeutic in all – and no-one knows how. We showed that ketamine improvement of treatment-resistant anxiety was linked to low frequency brain rhythmicity. We will, for the first time, assess brain activity and efficacy during ketamine therapy across a wide range of neurotic disorders. Our results should produce major theoretical advances and lead to new methods that could revolutionise treatment for patients with this broad group of stress-related disorders.