Maybe every friend has been yawning. In general, we think that people can involuntarily yawn when they are sleepy, which indicates that it is time to go to bed in the direction of work or recreation. But sometimes we yawn, and apparently not because we're sleepy (maybe waking up, or just walking on the road and yawning during the day). What is the reason for it?
What does yawning mean to us? Consider the following scenario: On a sunny afternoon, about 2 o'clock in the afternoon, you are driving on a long, straight country Road, and you are very eager to reach your destination. You are trying to stay alert and attentive, but sleep is coming to you.
You start yawning, and you may be restless and try to get out of the trap by other habits that might improve your waking level. However, the purpose of yawning is really to sleep? Yawning is usually caused by a few things, including tiredness, fever, stress, social and other psychological cues, and varies from person to person. Why we yawn, this problem has long been controversial in its field of study, after all, we have no evidence to point out the exact purpose of our yawning.
But there are several theories about the purpose of yawning, which include raising alertness, cooling the brain, and reminding your partner to take over the work in your hands and so on.
First, yawning can help us stay awake. It is known that yawning is accompanied by an increase in the number of trapped people, which leads to the awakening hypothesis of yawning. Yawning can lead to stretching, and increased restlessness may help keep you vigilant as your sleep pressure increases. During yawning, specific muscles in the ear (tension tympanic muscles) are activated.
This leads to an increase in the range and sensitivity of the tympanic membrane and hearing, thus increasing our ability to monitor the world around us.
Second, yawning can help cool the brain Another theory of our yawning is the thermoregulation hypothesis. This suggests that yawning can achieve the purpose of cooling the brain. Yawning causes deep breathing, breathing cold air into the mouth, and then cooling into the brain's blood. Proponents of the theory claim to have observed a rise in brain temperature before yawning, and to see a decrease in temperature after yawning. But the study suggests that excessive yawning may occur in the brain and during elevated body temperature.
It has no cooling purpose. When the experiment induces a fever phenomenon, it is possible to see an increase in the frequency of yawning, suggesting a correlation between the body's warming and yawning.
But there is no clear evidence that it will help the body cool down, or that it is only warming the body to the cause of yawning.
In addition, yawning also has ' sentinel ' duties Yawning is observed in almost all vertebrates, suggesting that reflection is ancient. Evolutionary-based behavioral assumptions treat humans as social animals. When we are vulnerable to attack by another species, mutual protection is an important function of our own community.
Part of our group collaboration involves the sharing of sentinel duties, and when a Sentinel becomes less vigilant, the yawning or stretching signal that emerges is important for the other sentinel to take responsibility for taking over the duties.
So what does neuroscience do to explain this? The reflex of yawning involves many structures in the brain. A scan of the brain that is prone to contagious yawning has found that the brain's medial prefrontal cortex activates during yawning, and the brain region is associated with decision-making.
Damage to the region can also lead to a loss of empathy. By stimulating specific areas of the hypothalamus, which contain neurons with oxytocin, it can cause yawning in rodents. It is well known that oxytocin is a hormone associated with social integration and mental health. Injecting oxytocin into different areas of the brainstem can also cause yawning. These include the hippocampus (associated with learning and memory), the ventral covered area (associated with dopamine release, happy hormones), and the amygdala (associated with stress and emotion).
Blocking the oxytocin receptor can prevent this effect. Patients with Parkinson's disease do not yawn as frequently as other patients, which may be associated with low levels of dopamine.
Dopamine substitutes have been shown to increase the frequency of yawning. Similarly, cortisol, a hormone that increases with stress, causes yawning, and removing the adrenal glands (releasing cortisol) prevents the loss of navigational behavior. This suggests that stress may play a role in triggering yawning, which may be the reason why your dog may yawn during a long-distance bus trip.
Thus, it seems that yawning has some relationship with empathy, stress and dopamine release.
Why is yawning contagious? If you're right, you may have at least one yawn at the time of reading this article. Yawning is a contagious behavior, and seeing people yawn often makes us yawn.
However, the only theory presented here is that the sensitivity to contagious yawning is associated with empathy for people. In general, neuroscientists have clearly understood the various types of yawning triggers, and we have described in great detail the mechanisms of yawn behavior.
But the purpose of yawning is still elusive. Back on our road trip, yawning may be a physiological implication, as the struggle between vigilance and sleep stress escalates.
