Several recent brain-scan studies have shown that yawning evokes a unique neural activity in the areas of the brain that are directly involved in generating social awareness and creating feelings of empathy. One of those areas is the precuneus, a tiny structure hidden within the folds of the parietal lobe. According to researchers at the Institute of Neurology in London, the precuneus appears to play a central role in consciousness, self-reflection, and memory retrieval. The precuneus is also stimulated by yogic breathing, which helps explain why different forms of meditation contribute to an increased sense of self-awareness.

But yawning doesn’t just relax you—it quickly brings you into a heightened state of cognitive awareness. Students yawn in class, not because the teacher is boring (although that will make you yawn as well, as you try to stay focused on the monotonous speech), but because it rids the brain of sleepiness, thus helping you stay focused on important concepts and ideas. It regulates consciousness and our sense of self, and helps us become more introspective and self-aware. Of course, if you happen to find yourself trapped in a room with a dull, boring, monotonous teacher, yawning will help keep you awake. Yawning will relax you and bring you into a state of alertness faster than any other meditation technique I know of, and because it is neurologically contagious, it’s particularly easy to teach in a group setting. One of my former students used yawning to bring her argumentative board of directors back to order in less than 60 seconds. Why? Because it helps people synchronize their behavior with others.

Dogs yawn before attacking, Olympic athletes yawn before performing, and fish yawn before they change activities. Evidence even exists that yawning helps individuals on military assignment perform their tasks with greater accuracy and ease. Indeed, yawning may be one of the most important mechanisms for regulating the survival-related behaviors in mammals. So if you want to maintain an optimally healthy brain, it is essential that you yawn.

So what is the underlying mechanism that makes yawning such an essential tool? Besides activating the precuneus, it regulates the temperature and metabolism of your brain. It takes a lot of neural energy to stay consciously alert, and as you work your way up the evolutionary ladder, brains become less energy efficient. Yawning probably evolved as a way to cool down the overly active mammalian brain, especially in the areas of the frontal lobe. Some have even argued that it is a primitive form of empathy. Most vertebrates yawn, but it is only contagious among humans, great apes, macaque monkeys, and chimpanzees. In fact, it’s so contagious for humans that even reading about it will cause a person to yawn.

It is true that excessive yawning can be a sign that an underlying neurological disorder (such as migraine, multiple sclerosis, stroke, or drug reaction) is occurring. However, I and other researchers suspect that yawning may be the brain’s attempt to eliminate symptoms by readjusting neural functioning. Numerous neurochemicals are involved in the yawning experience, including dopamine, which activates oxytocin production in your hypothalamus and hippocampus, areas essential for memory recall, voluntary control, and temperature regulation. These neurotransmitters regulate pleasure, sensuality, and relationship bonding between individuals, so if you want to enhance your intimacy and stay together, then yawn together. Other neurochemicals and molecules involved with yawning include acetylcholine, nitric oxide, glutamate, GABA, serotonin, ACTH, MSH, sexual hormones, and opium derivate peptides. In fact, it’s hard to find another activity that positively influences so many functions of the brain.

Also, very interesting how strongly 'anti-yawn' our mores really are