This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Mood Disorders, Subject name: Psychiatry
Disruption or disorganization of biological rhythm is observed in: 
Select and explain. 
A. Schizophrenia, B. Anxiety, C. Depression, D. Mania
C: Depression
Answer: C: Depression 
Explanation: There are characteristic disturbances of sleep (early morning insomnia and reduced latency of REM sleep) in depression.