Tears resulting from sadness, anger, fear or joy vary chemically from those caused by smelling onions and may be nature’s method of removing chemicals built up by stress from the body. Dr. William Frey II, of the Psychiatry Research Laboratories at the St. Paul-Ramsey Medical Center, St. Paul, Minn., believes this to be the case. Studies he has done indicate that women cry five times as often as men and that 85% of the women and 73% of the men thought that crying made them feel better. Most common reason for crying is sadness, followed in rank by happiness, anger, sympathy, anxiety and fear.

Source Unknown