Simply a mood disorder, depression may bring the feelings of hopelessness, sadness, numbness, anger, loss of energy, emotional distress, irritability, and abrupt changes in weight, appetite and sleep patterns. It causes impaired psychosocial functioning that badly affects an individual’s everyday activities. 

Depression has several possible causes such as family history (of some mood disorder), childhood trauma, drug or alcohol misuse and medical conditions (ADHD, chronic pain, insomnia, etc.)

Depressed people usually experience symptoms related to their emotional and physical well-being, behavioral patterns, sexual interests, sleep patterns and cognitive abilities. 

Treatment for depression mainly  focuses on reducing your symptoms. Medical practitioners may prescribe you antidepressants and antipsychotic medications.