The vagus nerve, which connects the enteric nervous system to the brain, is stimulated directly by gut bacteria. Gut microorganisms influence the structure of sleep and the hypothalamic-pituitary-adrenal axis's response to stress through these several methods. A current topic in psychiatry is the gut microbiota as a potential treatment target for mental disorders. In the human stomach, trillions of bacteria have been found to play a significant role in the communication between the gut and the brain by influencing neurological, immunological, and endocrine pathways. Evidence linking the gut microbiota to gastrointestinal and extragastrointestinal illnesses is growing. Anxiety and sadness, two conditions that are common in today's culture, have been related to dysbiosis and inflammation of the stomach.