well yes it is! they just rest! if they had their eyes shut the fluid in them would gather together and harden and they wouldnt be able to open their eyes! so they sleep with eyes open! i hope i have helped and i hope i have got this info correct!
Yeah all of mine sleep with their eyes open, very rare I see them shut... I love being able to see them dreaming, when their ears twitch and eyes flicker... I always wonder what they could be dreaming about
I have some piggies which shut their eyes however I would say that the majority of them do keep them open when sleeping. As lukey said, when a guinea pig is dreaming their ears flicker and sometimes their eyes will too. I remember the first time I saw my piggies dreaming it really scared me because I thought they might be having a mini seizure! lol
mine used to sleep with there eyes open but now they no me and that i wont hurt them they feel comfortable enough to close them, i think its because in the wild they have got to be on the look out for prey all the time thats why they sleep with there eyes open.