Laughter can be so medicinal that Norman Cousins used it to treat his illness.

Its good for health, for oxygenation of the tissue, it burns calories, it helps blood pressure, boosts the immune system and you relax more.

The origin of laughter: there are many different theories and here is one of them:

We view the world and come up with assumptions of real situations also known as scripts or frames (programs). When these frames are challenged, the discrepancy may cause us to find it funny. So Laughter is some form of inequality in our perspective of what is happening around us and what we were expecting to happen. We laugh because the condition seem ridiculous to us. If we have a good sense of humor and understand the joke – we laugh and we feel good. If we don’t, then the opposite happens and we are critical and cynical.

The inequality of the situation is a challenge to our logical perception of life and because of this and because there is no harm caused or danger – we find it funny. Laughter is also spontaneous and can occur for other reasons that are not so clear. Ultimately – a good laugh is good and it doesn’t matter how you start

A good, hearty laugh relieves physical tension and stress, leaving your muscles relaxed for up to 45 minutes after.

Laughter boosts the immune system. Laughter decreases stress hormones and increases immune cells and infection-fighting antibodies, thus improving your resistance to disease.

Laughter triggers the release of endorphins, the body’s natural feel-good chemicals. Endorphins promote an overall sense of well-being and can even temporarily relieve pain.

Laughter protects the heart. Laughter improves the function of blood vessels and increases blood flow, which can help protect you against a heart attack and other cardiovascular problems.

Laughter makes you feel good. And the good feeling that you get when you laugh remains with you even after the laughter subsides. Humor helps you keep a positive, optimistic outlook through difficult situations, disappointments, and loss.

More than just a respite from sadness and pain, laughter gives you the courage and strength to find new sources of meaning and hope. Even in the most difficult of times, a laugh–or even simply a smile–can go a long way toward making you feel better. And laughter really is contagious—just hearing laughter primes your brain and readies you to smile and join in the fun.

The link between laughter and mental health

Laughter dissolves distressing emotions. You can’t feel anxious, angry, or sad when you’re laughing.

Laughter helps you relax and recharge. It reduces stress and increases energy, enabling you to stay focused and accomplish more.

Humor shifts perspective, allowing you to see situations in a more realistic, less threatening light. A humorous perspective creates psychological distance, which can help you avoid feeling overwhelmed.

Be more spontaneous. Humor gets you out of your head and away from your troubles.

Let go of defensiveness. Laughter helps you forget judgments, criticisms, and doubts.

Release inhibitions. Your fear of holding back and holding on are set aside.

Express your true feelings. Deeply felt emotions are allowed to rise to the surface.

Resources:

Laugh.com

Wiki how to laugh

Laugh Factory

Why We Laugh - Ted Talk

Laugh USA