Malfunctions in the serotonin system can trigger an altered brain state. Serotonin is a powerful neurotransmitter that regulates mood, sleep, and etc. Abnormal levels are associated with depression, anxiety, Obsessive Compulsive Disorder, a suicidal tendency, and alcoholism Neurons in the reptilian or 1st brain layer produce serotonin, which is carried to the prefrontal cortex or 3rd brain layer by long projections. In suicide, neurons appear to send less than normal amounts of serotonin to the prefrontal cortex. Interestingly, 90 percent of all serotonin is found in the gut or Enteric Nervous System or Gastrointestinal Tract—with only 10 percent in the brain and central nervous system.