Crying releases extra stress hormones, which is why you feel better after crying!

Writer Victor Villasenor’s grandmother always said that crying cleans the soul. She was right. Crying has several health benefits. It releases extra stress hormones from the body and helps to expel toxins from the body. Crying is a way to express pain and joy. It is a nonverbal communication that asks others for help. 

Maybe that is where the idiom “cry for help” comes from. Psychologists believe that crying is an outlet for intense emotions like joy, surprise, and agony. People tend to remember positive aspects of crying and see it as a resolving of grief. 

This could very well be why people believe crying is helpful and good. Some scientists believe crying, in an evolutionary context, would help blur the vision of an aggressor and allow the weak to escape. 

It can also show vulnerability and gain the pity of an aggressor. All in all, crying is an expression of a multitude of emotions and feelings. 

(Source)