Naked Science Forum

General Science => General Science => Topic started by: John France on 05/05/2010 16:30:02

Title: Why do we cry sometimes whilst laughing?
Post by: John France on 05/05/2010 16:30:02
John France  asked the Naked Scientists:
Hello Chris,

Could you and your team try to answer this question for me (and maybe enjoy the research too-I'd recommend a Dara O'Briain show).

If tears are for lubrication and cleaning your eyes, why do you cry when you are really laughing?

With many thanks and keep up the good work (,

Janet France and family.

What do you think?
Title: Re: Why do we cry sometimes whilst laughing?
Post by: StephenJones011 on 07/05/2010 13:25:33
Hi John

 good question. Laughing to the point of tears involves emotions, we cry in response to emotion, either good or bad, because of signals from higher centers in our brain that tell our tear glands (the lacrimal gland) that we're sad or happy. These signals travel through the parasympathetic pathways, the part of our nervous system that controls, among many other things, bodily secretions such as tears. These signals are part of complicated patterns of emotion that our body instinctively recognizes. If we look at other things our body is doing while we weep, it's not too surprising that we can cry while laughing also. The facial expressions of laughing and crying are similar, and even our breathing pattern is similar (First we take a long deep breath, and then we let out short, sharp breaths, in both laughing and weeping)