Mental illness are the health conditions that involving significant changes in thinking, emotion and/or behavior, distress and problems functioning in social, work or family activities. Mental illness refers collectively to all diagnosable mental disorders.
Examples of signs and symptoms from mayoclinic:
1. Feeling sad or down
2. Confused thinking or reduced ability to concentrate
3. Excessive fears or worries, or extreme feelings of guilt
4. Extreme mood changes of highs and lows
5. Withdrawal from friends and activities
6. Significant tiredness, low energy or problems sleeping
7. Detachment from reality (delusions), paranoia or hallucinations
8. Inability to cope with daily problems or stress
9. Trouble understanding and relating to situations and to people
10. Alcohol or drug
abuse11. Major changes in eating habits
12. Sex drive changes
13. Excessive anger, hostility or violence
14. Suicidal thinking