do dogs sleep with their eyes open

Dogs do not usually sleep with their eyes fully open. What appears to be open eyes during sleep is often an illusion caused by the dog's eye anatomy, specifically the presence of the third eyelid or nictitating membrane, which covers and protects the eye even when the eyelids appear open. Sometimes, dogs do sleep with their eyes partially open, especially during lighter sleep stages or the REM phase when they are dreaming. This behavior is normal and related to their sleep patterns and evolutionary instincts to stay somewhat alert. Additionally, certain breeds with bulging or large eyes might look like they sleep with eyes open more frequently. Overall, it is not harmful and usually a natural behavior, although if the dog exhibits other unusual symptoms, a vet's advice is recommended.