__1. Mirror effect__ Yawning can be contagious. We start yawning when we see someone doing it, even if it is just a photo or video. This phenomenon is triggered by the so-called mirror neurons in the cerebral cortex. They get excited when we watch what others are doing and help us imitate and feel empathy. This is why studies of people with autism have shown that they don't yawn. Children under five years of age are also not prone to mirror yawning as they cannot feel empathy for others. __2. Breath of fresh air__ When you feel sleepy, tired, or bored, it triggers mental braking processes, including slower, less frequent, and shallower breathing, which leads to an excess of carbonic acid and other metabolic waste in your blood. When these affect the respiratory centers of the brain, it provokes yawning. __3. Brain thermoregulation__ There is a theory that when we yawn, our brain gets ===a portion of fresh air and cools down. Studies have shown that during the cold season, people yawn more often than during the warm season. Cooling down the brain gives a boost of energy, so we yawn after a sleepless night. __4. Stretching and waking up__ Another purpose of yawning is to stretch and relax the muscles of the throat, tongue, and rest of the body since we often stretch after yawning. Such warming up helps our body wake up and go to action. For the same reason, people yawn when they feel sleepy or bored since yawning helps to wake up the brain and the stiffened muscle. __5. Relieving ear congestion__ During the flight, yawning helps relieve ear congestion, which occurs because of the pressure difference on opposite sides of the eardrum. Since the throat is connected with the middle ear cavity through special channels, yawning helps to even out the pressure in the ears. __6. Symptom of a disorder__ Frequent, prolonged yawning can be a sign of various disorders such as disorders of body thermoregulation, sleep problems, high blood pressure, thrombosis, or damage to the brain stem where the respiratory center is located. Heart attacks stimulate the vagus nerve running from brain to gut, which leads to excessive yawning. Those who suffer from constant yawning should consult with a medical professional and check the blood pressure as well as the state of heart and blood vessels. __7. Antidepressant__ Yawning frequently can occur in the state of anxiety, stress, or depression. When we yawn, the airways open wide, the muscles relax, and, for a split second, we experience a pleasant state of partial loss of consciousness. This helps relieve stress, fatigue, and psychological strain.