My girlfriend sleeps with her eyes half open. Why?

About some people sleeping with their eyes half open: this is normal! In theory, anyone can sleep with his eyes open. Generally speaking, the function of opening eyes and closing eyes is accomplished through the contraction and relaxation of extraocular muscles and expression muscles, especially levator palpebrae superioris and orbicularis oculi muscles. When sleeping, the nerve has weak control over the muscles, and the tension of the orbicularis oculi muscle is low or the levator palpebrae superioris muscle is not relaxed enough, which may lead to incomplete eye closure. Some diseases can also cause eye insufficiency, such as "acute facial neuritis". Don't worry about this kind of problem, and it won't affect sleep. When you sleep, your eyes are dormant and will not respond to external stimuli.