Do eye muscles relax when you close your eyes?
I would guess that the eye muscle relaxes when the eye is closed. After having the eyes closed, just in the moment after opening them, it seems that the focus is in the distance. It takes a fraction of a second before you can read some text on your computer screen for example . This focusing-duration seems to be shorter when looking into the distance after opening the eyes.

Another effect is when you look at an object in short range for quite a moment and then close your eyes. You can feel the relaxation.