I think the saying that 'laughter is the best medicine' is probably quite close to the truth. Certainly, it has many benefits. I only looked quickly but this is one of a few studies from PubMed:

The therapeutic value of laughter in medicine

I love this bit, taken from the conclusions: Adverse effects are very limited, and laughter is practically lacking in contraindications. Well thank goodness for that ;-).

I do agree that adults probably hold back when it comes to laughter. Sometimes when I'm alone and I read / see something really funny, I will try not to 'censor' myself and let my body dictate how hard I laugh (and convulse and judder...!). It's fantastic. I was ill the other week and was sat on the sofa watching a comedy, and I must have burst out into full proper laughter five or six times. Not saying anything came of this directly but I was back at work the next day feeling much better. I certainly felt less sorry for myself at the time as well.

you know,I've thought the same thing myself. Nothing feels as good as letting go and laughing with pure abandon!

I would agree that most adults don't let loose on a good laugh. I, for one, love it when I'm crying because I'm laughing so hard. To each their own!

Desmond Morris talks about the origins of the laugh in "The language of the body". I've been looking for the right reference on the internet, can't find it, I see this on another forum:

Desmond Morris proposed that a laugh is an aborted cry. He cites the fact that an individual's first laugh is usually for that individuals mother or father, and is a response to a situation that would normally be considered alarming, or even frightening. His take is that the infant then begins to cry, and stops themselves abruptly with a realization something akin to, "this is frightening, but Mom does not appear alarmed, so it must be OK".

Nothing like a babies laugh to make you laugh. Our son started to laugh really early - and he's still a hearty laugher - they say at daycare he'll have a good belly laugh at least once a day.

Proud mommy video: http://www.youtube.com/watch?v=BHw5kU37DQE

I think as adults we dont let go enough to have a good laugh - being a parent has helped let go for me - I laugh much more now and often in public! It helps so much with mood.

I went through a phase when I unintentionally sounded like a french frog. Uhhuhuhuhuhuuu. Oui.

i think it has something to do with growth hormone and stem cell production. children are bursting with these chemicals and are in some way "high" much of the time. if youve done any drugs in your adult years you know what i'm taking about as many drugs reconfigure of chemicals into these sorts of states, but we usually have a type of hangover afterwards because we lack the nutrients to heal quickly.

I have found I laugh differently around my sister than around others. Our laughs somehow morph until they sound exactly alike. I don't know if I do this around other people because my sister and I have that strange ability to make each other laugh at anything and everything until we're laughing for seemingly no reason except to laugh. 8)

I love laughing and rarely hold back!