How come single eyelids become double eyelids after sleeping

I believe that many people want to have double eyelids, and some people will occasionally have double eyelids, that is, after a night's sleep, their single eyelids will become double eyelids, but after a while they will become single eyelids again. Many people want to know what causes this situation. Let me introduce some of them below. So, how can single eyelids become double eyelids after sleeping?

First, how does a single eyelid become a double eyelid after sleeping? The medical name for eyelids should be eyelids, which are two movable eyelid covers located in front of the eyeball, forming a barrier to protect the eyeball. To protect the eyeball and its outermost cornea which is easily injured, and to spread tears to the entire conjunctiva and cornea. For some people, there is a very obvious groove on their upper eyelids when they open their eyes. This is what we call double eyelids. However, for some people, there is no such groove on their eyelids, and the entire upper eyelid is smooth, which is called single eyelids.

Second, generally speaking, whether the eyelid is single or double has a lot to do with the structure of the upper eyelid, among which the key roles are played by two small muscles on the eyelid: the orbicularis oculi muscle and the levator palpebrae superioris muscle. Simply put, the orbicularis oculi muscle is the muscle responsible for closing the eyes. It grows around the entire eye. The "eyelid twitching" we often talk about is the twitching of the orbicularis oculi muscle caused by abnormal nerve excitement. The levator palpebrae superioris is the muscle responsible for opening the eyes. It is connected to the tarsal plate on the eyelid. If this muscle atrophies and declines, a person's vision will be greatly affected.

How does a single eyelid turn into a double eyelid after sleeping? If a person's upper eyelid skin and subcutaneous fat are thin, and the orbicularis oculi muscle and levator palpebrae superioris muscle are very developed, when the eyes are opened, the orbicularis oculi muscle and the levator palpebrae superioris muscle will move in coordination to form a wrinkle on the upper eyelid, which is a double eyelid. However, if a person's upper eyelid skin and subcutaneous fat are thicker, the orbicularis oculi muscle is more developed but the levator palpebrae superioris muscle is underdeveloped, the orbicularis oculi muscle moves during the process of opening the eyes, but the levator palpebrae superioris muscle cannot move the tarsal plate and the surrounding skin on the eyelid, and wrinkles will not form on the eyelid, resulting in single eyelids.