Even blind people can not sleep with their eyes open. If the eyelids do not close when people are sleeping, the bacteria will get into the eyeballs and corrode them, and then the corrosion will be transmitted to the nerves of the eyes, thus damaging the eyes. However, in some cases, some people will half open their eyes when they are asleep. There are mainly two reasons for it. First of all, these people have insufficiency of the spleen caused by disorder of diet, disorder of working and resting, or long time of disease. The other people who sleep with half open eyes may be born to sleep in this way. In this case, people should make sure that their sleeping environments are dar enough, and the darker, the better. Becuase the darkness can do less damage to the eyes when people are asleep. The function of eye opening and closing are completed by the extraocular muscles and mimetic muscles, especially through the shrinkage and relaxation of the levator palpabrae muscles and the orbicularis oculi muscle. If the nerves have very weak control to the muscles when people are sleeping, or if the orbicularis oculi muscles have low tension, or if the levator palpabrae muscles have weak contraction, it can be hard for the eyes to be closed completely. Some diseases can also lead to incomplete close of eyes, such as acute facial neuritis. If so, people should go to the doctor's as soon as possible in can that the conditions get worse.