Laughter has been used as a therapy in medical situations in many parts of the world. The earliest one I have found was 1977 but I am sure it is one of those areas that has always been around with people joking to lift their spirits during adversity.
On the science side we know that there is a feedback from the muscles to the brain. One consequence of this is that it is that the tension in muscles during anger reinforces that feeling of anger. Relaxing the muscles actually counteracts that anger feeling.
Similarly expressions on our faces reinforce the feeling that the expression shows because of the feedback to the brain from our face muscles. Thus smiling really does make you feel happier and you can use a smile to counteract a lower mood.
Well if smiling is beneficial what can laughter do? Well it can do quite a lot. It has been shown to decrease stress levels and the experience of pain and raise mood.
It increases the secretion of nitric oxide in blood vessels which lowers blood pressure and decreases the development of arterial disease.
It lowers the levels of cortisol in the blood thus enhancing the activity of the immune system.
Laughter groups have grown up in different parts of the world.
For example in 1995 Dr Madan Kataria studied the beneficial effect of laughter and started a Laughter Yoga group in India in a local park with just 4 other people. Within a few days many others joined them just to have a good old laugh.
Since then it has spread to many other cities in the world.
Laughter Yoga starts with a few deep yogic breaths and proceeds with a range of playful laughter exercises that
lower our inhibitions about laughing. Laughter can initially be forced because it is infectious and then becomes real.
There are many other examples for instance the Humor Project in the USA and the employment of clowns for children’s wards.