Why can t some people sleep with their eyes completely closed?

Because their nervous system is not well developed. When sleeping, your eyes open unconsciously. But in fact they were already asleep.

It may be caused by eye disease, nerve causes, or orbital deformity.

In fact, there are also people who sleep with their eyes open, but most people don't have this function, if you think it's okay, you can also try to sleep with your eyes open, it is estimated that it is difficult to do.

Human nature, sleeping with your eyes open is different.

From a physiological point of view, the natural state of human eyelids is drooping, that is, when the human brain no longer controls the eyelid (eyelid) muscles, the human eyelids are drooping, that is, the human eyes are closed. When people sleep, the higher nerve centers of the brain are inhibited, so the muscles that control the eyelids must be inhibited and lose control of the eyelid muscles, so people sleep with their eyes closed.

From the perspective of adaptation of organisms to the environment: organisms and the environment in which they live are adaptable, during sleep, people's defense of the external environment is limited, and for animals, the role of the eyes is incomparable, and closing the eyes can play a protective role in it. Moreover, the human eye needs to be moistened, otherwise the cornea will become blurred and even blind, and closing the eyes can keep it moist enough.

Moreover, when a person is sleeping, the visual center is in a state of inhibition, so that even if the eyes are open and the object is imaged in the eye, the brain still cannot perceive it, which was the case before Zhang Fei was killed.

From the point of view of biological evolution: terrestrial animals, from frogs to other reptiles, birds, and mammals, all have their eyes closed when they sleep! Of course, humans have inherited it without hesitation!

When relaxed, all muscles are relaxed, including the eyelids. And the eyes need to be kept moist, and the tear glands will ensure that the normal activities of the eyes are not affected. But when people sleep, the tear glands are also in a resting state, and without rear supplies, the eyes have to be closed.

Biological truth, this is biological truth.

Sometimes people are in the process of falling asleep, if they don't think about anything, if they remain in a state of accidental unconsciousness, sometimes their eyes are half-open. This is normal. ，

People with a weak spleen sleep with their eyes open. It is usually half-opened. But some people are indeed born to sleep with their eyes half-open.

The darker the environment when such people sleep, the better, so as to minimize the damage to the eyes. Usually such people have poor eyesight.

In this case, it should be said that there is not necessarily anything abnormal. Most people's eyes are naturally closed when sleeping, and some people are not completely closed, and Zhang Fei is described in China's classical masterpiece "Romance of the Three Kingdoms" as sleeping with his eyes open. At present, we have not seen any authoritative reports of "lack of a certain trace element" causing sleep with the eyes open.

The opening and closing of the eye is accomplished by the contraction and relaxation of the extraocular and expressive muscles, especially the levator palpebrae superioris and orbicularis oculi muscles. Weak innervation of muscles by nerves during sleep, low tone of orbicularis oculi muscle, or insufficient relaxation of the levator palpebrae muscle may result in incomplete closure of the eye. Some disorders can also cause insufficiency of the eye, such as "acute facial neuritis."