Symptoms of Mental Illness
Symptoms of mental illness will vary depending upon the type and severity of the condition.  Some may be short term symptoms caused by extreme stress or extended exposure to stressful situations.  Other situations may persist over long periods of time.  Some general symptoms that may suggest a mental illness include:

Depression
Confused thinking
Inability to concentrate
Frequent sadness or persistent irritability
Reduced function at work
Extreme highs and lows in mood
Excessive fear, worry, or anxiety
Panic attacks
Social withdrawal
Dramatic changes in eating or sleeping habits

Strong feelings of anger
Delusions or hallucinations (seeing or hearing things that are not really there)
Increasing inability to cope with daily problems and activities
Thoughts of suicide
Behavioral issues
Denial of obvious problems
Many unexplained physical problems
Abuse of drugs and/or alcohol