Psychosis is a mental disorder caused by a person becoming disconnected from reality. Symptoms may include delusions and hallucinations, among other features. Additional symptoms are incoherent speech and behavior that is inappropriate for a given situation. There may also be sleep problems, social withdrawal, lack of motivation, and difficulties carrying out daily activities. Psychosis can have serious adverse outcomes. As with many psychiatric phenomena, psychosis has several different causes. These include mental illness, such as schizophrenia or schizoaffective disorder, bipolar disorder, sensory deprivation and in rare cases, major depression (psychotic depression). Other causes include: trauma, sleep deprivation, some medical conditions, certain medications, and drugs such as cannabis, hallucinogens, and stimulants. One type, known as postpartum psychosis, can occur after giving birth. The neurotransmitter dopamine is believed to play an important role. Acute psychosis is considered primary if it results from a psychiatric condition and secondary if it is caused by a medical condition or drugs. The diagnosis of a mental health condition requires excluding other potential causes. Testing may be done to check for central nervous system diseases, toxins, or other health problems as a cause. Treatment may include antipsychotic medication, psychotherapy, and social support. Early treatment appears to improve outcomes. Medications appear to have a moderate effect. Outcomes depend on the underlying cause. In the United States about 3% of people develop psychosis at some point in their lives. The condition has been described since at least the 4th century BC by Hippocrates and possibly as early as 1500 BC in the Egyptian Ebers Papyrus. Signs and symptoms Hallucinations A hallucination is defined as sensory perception in the absence of external stimuli. Hallucinations are different from illusions and perceptual distortions, which are the misperception of external stimuli. Hallucinations may occur in any of the senses and take on almost any form. They may consist of simple sensations (such as lights, colors, sounds, tastes, or smells) or more detailed experiences (such as seeing and interacting with animals and people, hearing voices, and having complex tactile sensations). Hallucinations are generally characterized as being vivid and uncontrollable. Auditory hallucinations, particularly experiences of hearing voices, are the most common and often prominent feature of psychosis. Up to 15% of the general population may experience auditory hallucinations (though not all are due to psychosis). The prevalence of auditory hallucinations in patients with schizophrenia is generally put around 70%, but may go as high as