Almost twenty-five-years ago, Norman Cousins claimed, in his book Anatomy of an Illness, that laughter cured him of a rare debilitating disease. Ever since people have been attributing all kinds of benefits to laughter and humor. Some of it can be documented, some cannot.

For example, you may have heard that children laugh 400 times a day but adults only fifteen. Anyone who hangs around children for a while knows that they laugh a lot. But 400 does seem excessive. So I asked my humor colleagues if they know the source of this information.

Guess what? None of them did.

The closest any of them could up with was from a study which showed that "glee" (not just laughter) in a nursery school did range from 18.4 to 45 incidents an hour per child. While "glee", described in the dictionary as jubilant delight and joy, might contain periods of laughter, it does not indicate a period repeated laughter.

So, the jury is still out on the notion that kids laugh 400 times a day.

Adult laughter, on the other hand, is a little easier to track down. The book, American Averages, clearly states that "The average person laughs 15 times a day".

Another popular idea is that endorphins are secreted into the blood system when we laugh. Unfortunately, this has not been proven in the scientific world. What has been proven, by Dr. Lee Berk of Loma Linda University, is that cortisol, an immune suppresser, is less prevalent in the blood when we laugh. In addition, hearty laughter also produces other chemicals which help boast the immune system.

What we also know is that laughter oxygenates the blood (so we think better after a laugh), relaxes our muscles (maybe that's why we leak when we laugh) and raises, then lowers, our heart rate and blood pressure (similar to aerobic exercise).

While most of us know that we feel better after a good hearty laugh, science, in many cases, is yet to prove why. But that doesn't mean that we should stop laughing. After all, how many centuries did it take to prove that the world was round?