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A Mystery Signal: Yawning
Nov 1, 2015

Humans were created to be aware of our surroundings. We pick up on what is happening around us, and inside us, via certain signs. Every organism has a body language. And every body generates various signals, such as sneezing, shaking, or yawning, to express its state.

It is essential to listen to this language and to pay attention to these signals in order to take measures to prevent diseases. One must get warm when one feels cold, calm down when one is angry and sleep when one is tired.

Yawning is one of the body's most significant signals. It starts in the mother's womb and is seen throughout one's lifetime. It stems from causes like tiredness, lack of motion, boredom, listening to monotonous talk or music, being in an oxygen poor environment, observing another yawning person, sleep deprivation, or lack of healthy sleep – in addition to pathological reasons such as epilepsy, brain infection, vascular diseases of the brain, and backside brain tumors.

While certain substances are responsible for transmitting the neural signals in the brain trigger yawning, some also act to prevent it. For instance, when endorphin levels increase, yawning decreases; but yawning increases when levels of dopamine or serotonin are elevated. Certain drugs can also lead to yawning. Continuous yawning or failing to yawn, or chronic incomplete yawning, is considered a symptom of disease.

It is well known that people who are trying to be awake are seen to yawn more than a person who is sleepy. Since the heart rate is accelerated during yawning, the amount of blood sent to the lungs and brain is improved. Because of the increased energy output, sleep is delayed, to a certain extent. The oxygen demand of the body varies throughout the day depending on the conditions. The most oxygen dependent organ is the brain. As the result of a lowered oxygen ratio in the blood, yawning occurs and the brain's demand for oxygen is satisfied.

While sleeping, people recover from stress and anxiety. Yawning is a reminder to the body that the time for sleep has arrived. If a person cannot get enough sleep, they may struggle to focus, become nervous, or frequently yawn. Furthermore, synthetic clothing and rubber footwear are also listed among causes that lead to yawning, since these materials can cause increased levels of static electricity to accumulate in the body. The accumulated charge results in stress and exhaustion, therefore triggering yawning.

In a study, it was shown that 75% of people yawn in the morning, 50% at the end of the day, 30% after meals, and 47% while stretching. Scientists also discovered a relationship between yawning and brain temperature. Yawning was observed to stop during breathing through the nose, which cools the forehead. In this sense the brain resembles a computer; it works better when cooled. Yawning also cools the brain and therefore makes it function more efficiently. In other terms, yawning works like a fan on a computer. Exhaustion and insomnia trigger yawning because these increase brain temperature.

There are other factors that cause yawning. The over consumption of coffee and tea means more stimulants in the body. Caffeine stimulates the brain for more energy consumption. Thus, if sleep is postponed, due to the increased temperature, yawning is observed. If people grow dehydrated, they may also yawn. Therefore, experts recommend drinking water regularly. Talking on the phone for a long time tires the brain, and can cause yawning. Taking a shower with water warmer than the body temperature also leads to yawning because it stimulates an excessive secretion of hormones that cause sleepiness. Thus, it is better to take showers with very warm water in the evening and with less warm water in the morning.

Yawning becomes frequent when acidic beverages are excessively ingested, when exposed to noise for extended periods, during extreme exhaustion, or prolonged exposure to fluorescent lighting.

As in the case of acidic drinks, some individuals may display sensitivity and intolerance towards different foods. For example, celiac patients have a hard time digesting starch. They suffer from yawning, headaches, and exhaustion when they ingest starch. In young people and among individuals who consume salty foods, due to the increased accumulation of static electricity, yawning is more common. In addition, yawning also is witnessed during psychological stress. For instance, parachuters before they jump off the plane, athletes before starting a race, students before entering an exam, passengers before departure, and musicians preparing for a concert … all were observed to yawn frequently.

Hypothalamus and yawning

The hypothalamus, which forms the small portion at the front of the brain and maintains communications between the brain and the endocrine system with the pituitary gland, is assigned very important tasks, such as controlling excitement, hunger and thirst, sleep, blood pressure, and body temperature. The body responds to problems regarding these controls by yawning. For example, in cases when a high oxygen demand movement is made, the hypothalamus stimulates the lungs for more air and causes a person to yawn. From this point of view, the center responsible for yawning is believed to be located at hypothalamus.

Is yawning contagious?

Yawning is contagious, just like laughing. It is known that yawning is observed in people who witness somebody else yawning, hear somebody yawn – and even in people who think about yawning or read an article about it. A psychologist determined that yawning is contagious after making students watch people yawn, discovering that around 50% of the people who see a yawning person also yawn within a short amount of time. Experts note that the imitation of other people yawning can be an empathic reflex.

The facial expressions of yawning individuals are predicted to have an effect on other people – and that these expressions promote yawning! Mirror neurons in the brain are activated; therefore yawning takes place by feeling what the other person is experiencing.

Mirror neurons are cells that are affected by the observation of certain behaviors, especially among vertebrates watching members of their own species. It has been discovered that kids who are under the age of five are not affected by watching others yawn since their empathy and mirror neuron connections are not fully developed. The regions of the brain activated during contagious yawning and empathic behavior are the same. However, for non-contagious yawning people, these regions were found to be inactive. Therefore, yawning is more frequently observed in people who have improved emphatic skills. For instance, it has been determined that individuals suffering from heavy hearing loss do not display contagious yawning.

Do animals also yawn?

Yawning is not unique to humans; it can also be observed in some animals. When animals like lions, tigers, cats, dogs, hippopotamus, and even iguanas yawn, they open their mouths and extend their tongues, which can be frightening. Animals like horses, rabbits, penguins, and goats yawn with their eyes half closed, giving them a placid, funny look. A majority of animals yawn when they encounter a situation requiring attention, though it is also considered a possible form of communication for animals living in congregations. As in humans, it's believed that yawning helps to regulate body temperature. The brain temperatures of yawning mice were reported to become normal.

Yawning and washing

There is a static electric balance in the human body. Maintaining this balance is necessary for our health. Yawning serves as a symptom of some psychosomatic diseases that disrupt this balance. Contact with water and soil is one way our body regulates its static electricity when warned of an imbalance through yawning. This is why washing our body with a shower or with practices like ablution refreshes the skin and nervous system by helping achieve this balance. But washing the head, hands, and feet as in ablutions, the farthest parts of the body where blood vessels branch out, is especially useful. If the water is warm, vessels expand; if the water is cold, they contract, which provides elasticity and fitness.

Further reading

  1. Iacobani M. 2009. "Imitation, empathy and mirror neurons," Annual Review Psychology.
  2. Walusinski O. 2009. Yawning in diseases, European Neurology.