Why do you cry when you are sleepy Why do you still have a runny nose when you are sleepy?

Tears have the effect of protecting the eyeball, so tears are secreted all the time and flow on the surface of the eye all the time. It's just that we usually secrete very few tears, and we can't feel them. Tears flow into the nasal cavity through the nasolacrimal ducts, and new tears are secreted, so the tears can be metabolized without flowing out.

However, when the nasolacrimal duct is squeezed by muscles or external forces, the flow of tears will be blocked, and over time, tears accumulate more and more in the eyeball, and eventually flow out. Sleeping, laughing, yawning, and tears when sneezing are all for this reason.

This is normal! It's all about people.

When I'm sleepy, I always yawn. When you yawn, your eyes will always be full of tears, why do people shed tears when they yawn?

Human tears are secreted all the time, flowing on the surface of the eyeball. However, there is very little tears secreted and they flow along the surface of the eyeball and in the tiny spaces inside the eyelids, so you don't feel that the tears are flowing.

However, in the blink of an eye, the tears on the surface of these eyeballs are sucked into the nasolacrimal duct, the sewer of the tears. Don't underestimate this not-so-long tube, it's the only way for tears to reach your nose. The lacrimal glands constantly secrete tears, and the nasolacrimal ducts constantly excrete tears, so people usually do not shed tears.

When a person yawns, his mouth is wide open, and he may exhale more than he can out of his body in order to exhale carbon dioxide and inhale oxygen. With the action of yawning, a stream of gas exhales forcefully from the mouth. The muscles of the cheeks, tongue and throat tense and contract, and the pressure in the mouth and nose increases.

As a result of the increased pressure in the nasal cavity, it will temporarily block the work of the nasolacrimal duct to excrete tears, and the "sewer" will not be passed, and the tears will not flow, and more and more tears will accumulate in the eyes. There will be tears in his eyes, and finally he will burst out of his eyes and flow to his face.

In fact, not only yawning can cause tears, but also when people laugh, sneeze, cough, and vomit, and the reason is the same.

In addition, when the eyes feel particularly tired, secretions are secreted to reduce the burden on the eyes, so that the eyes are less tired.

Therefore, when people are sleepy, they will be astringent and tearful, and the body will send out such a notification to inform the information that they are tired and their body can no longer support it, and they will be astringent, and the purpose is to let you rest.

Because when we are sleepy, it causes the brain to be deprived of oxygen, and the lack of oxygen in the brain causes us to take a deep breath, squeeze out tears, and flow into the nose, which becomes snot.

Tears and runny nose when you are sleepy is a physiological reaction in humans, and it is the body that reminds you that you need to rest.

It may be because the brain is too tired, and the breathing is heavier when sleepy, resulting in a lack of oxygen to the brain, and when the brain is deprived of oxygen, it will make people yawn, and when they yawn, they will have tears and runny nose.

Why do people shed tears when they yawn?

Human tears are secreted all the time, flowing on the surface of the eyeball. In the blink of an eye, the tears on the surface of the eyeball are sucked into the nasolacrimal duct, the sewer of tears, so people usually do not shed tears.

When people are sleepy, they yawn and open their mouths wide so that they can exhale carbon dioxide and inhale oxygen. When you yawn, the muscles of the cheeks, tongue and throat contract, increasing pressure in the mouth and nose. The increased pressure in the nasal cavity will block the nasolacrimal duct from excreting tears, and the tears will not flow, and the more tears will accumulate in the eyes, and two tears will appear, and finally they will come out of the eyes and flow to the face.

If you use your eyes for too long, your eyes will be dry and you will secrete fluid to moisten your eyes. Blink frequently when using your eyes for long periods of time.