Why does laughter sometimes bring us tears ?

Laughing to tears is not unusual whenever we listen to several good jokes in a row or even when we are playing with our kids or pets at home and they  surprise us with funny tricks and questions.These body reactions of bursting into tears or bursting into laughther  are very healthy indeed.There are several studies that show the good effects on our bodies after we cry or laugh a lot  ! Can you see any similarities  between crying and laughing ? 

Click on the links below to read about this issue,ok ?

http://www.dailymail.co.uk/sciencetech/article-2840002/The-science-Bieber-fever-Researchers-reveal-cry-tears-joy-laugh-bad-news.html

http://www.dailymail.co.uk/sciencetech/article-2840002/The-science-Bieber-fever-Researchers-reveal-cry-tears-joy-laugh-bad-news.html

Which proverb do you like best ? You can write about your favorite one at the bottom of this post,can't you ?