sleeping with eyelids half open

My daughter is five years old.  Ever since I can remember she has been sleeping with her eyes half open.  I am now trying to get her to close her eyes so she can put her head underwater in the pool. She said that it hurts when she tries to close her eyes all the way. When she was younger I would ask her to close her eyes and she would tell me that she doesn't know how. I am now thinking that their's some other underlining problem here that I am not noticing. I am trying to figure out what would cause something like this and why.  If you could give me any info and input on this that would be great. Thanks

[alan20002000]

i think she has some problem with the muscles that move he eye
its better to be seen by a doctor
some time its infection and can spread further