An illness developed after birth, usually in young adulthood or adolescence that impairs the individual’s thinking and emotional balance. The most common conditions are schizophrenia, schizoaffective disorder, personality disorder, bipolar and depression. Those with a diagnosis of mental illness may suffer from psychosis, hallucinations and delusions (Loss of reality and seeing or hearing things that aren’t there) but this is normally only in very severe cases. Mental illness fluctuates and can be controlled extremely successfully by therapy and medication, but individuals may experience relapses at any time. Again, severity directly affects a person’s acceptability of their diagnosis, but individuals are often observed to have insight into their illness during bouts of good health but may display denial or poor understanding during or leading up to relapse.