During digestion, the movements of the stomach are similar to churning. Every time you take a full breath, or when you cachinnate well, the diaphragm descends and gives the stomach an extra squeeze and shakes it.
Frequent laughing sets the stomach to dancing, hurrying up the digestive process. The heart beats faster, and sends the blood bounding through the body." There is not," says Dr. Green,"one remotest corner or little inlet of the minute blood-vessels of the human body that does not feel some wavelet from the convulsions occasioned by a good hearty laugh." In medical terms, it stimulates the vasomotor centers, and the spasmodic contraction of the blood-vessels causes the blood to flow quickly. Laughter accelerates the respiration, and gives warmth and glow to the whole system. It brightens the eye, increases the perspiration, expands the chest, forces the poisoned air from the least-used lung cells, and tends to restore that exquisite poise or balance which we call health, which results from the harmonious action of all the functions of the body. This delicate poise, which may be destroyed by a sleepless night, a piece of bad news, by grief or anxiety, is often wholly restored by a good hearty laugh.