By mayo clinic
A good laugh has great short-term effects. When you start to laugh, it doesn't just lighten your load mentally, it actually induces physical changes in your body. Laughter can:
Stimulate many organs. Laughter enhances your intake of oxygen-rich air, stimulates your heart, lungs and muscles, and increases the endorphins that are released by your brain.
Activate and relieve your stress response. A rollicking laugh fires up and then cools down your stress response and increases your heart rate and blood pressure. The result? A good, relaxed feeling.
Soothe tension. Laughter can also stimulate circulation and aid muscle relaxation, both of which help reduce some of the physical symptoms of stress.
Laughter isn't just a quick pick-me-up, though. It's also good for you over the long haul. Laughter may:
Improve your immune system. Negative thoughts manifest into chemical reactions that can affect your body by bringing more stress into your system and decreasing your immunity. In contrast, positive thoughts actually release neuropeptides that help fight stress and potentially more-serious illnesses.
Relieve pain. Laughter may ease pain by causing the body to produce its own natural painkillers. Laughter may also break the pain-spasm cycle common to some muscle disorders.
Increase personal satisfaction. Laughter can also make it easier to cope with difficult situations. It also helps you connect with other people.
Improve your mood. Many people experience depression, sometimes due to chronic illnesses. Laughter can help lessen your depression and anxiety and make you feel happier.