This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sedative-Hypnotics and Parkinsonism, Subject name: Pharmacology
Increased tendency to fall asleep at night without causing central nervous system depression is a propey exhibited by: 
Select and explain. 
A. Pyridoxine, B. Diphenhydramine, C. Melatonin, D. Ethanol
C: Melatonin
Answer: C: Melatonin 
Explanation: -Melatonin is an endogenous hormone secreted by pineal gland. -It regulates day night cycle. -It causes increased tendency to fall asleep at night without causing central nervous system depression