Have you ever seen a cat sleeping with its eyes open, like this?

It may look like they're pretending, but they are really asleep! Today we’ll explain why cats sleep with their eyes open, and also touch on the third eyelid.

Why Cats Sleep with Their Eyes Open

1. Is it normal?

Yes! It’s completely normal. Cats can even twitch or dream while sleeping with eyes open.

2. Seven reasons behind open-eye sleeping

Reason One: Light Sleep

Sleeping with eyes open is often because the cat is in a light sleep stage. Cats are easily awakened by small sounds or touch. These short sleep periods help conserve energy for night hunting. Cats may also respond to weather; in cold or damp conditions, they may enter shallow sleep more frequently.

Reason Two: Noisy Environment

Even indoor cats may feel cautious in a noisy environment, especially when many people or strangers are around. Cats may hide to sleep, but keep one eye open to monitor potential danger. Providing a quiet, dark space with familiar items like blankets or toys can help cats sleep more deeply.

Reason Three: Eye Injury

Fights or accidents can leave scratches on the eyes or eyelids, potentially damaging the third eyelid or causing corneal ulcers. Eye injuries are painful and may show as redness, swelling, tears, inability to close eyes, or constant pawing at the eyes. Minor injuries can be treated with eye drops, but severe cases should be examined by a veterinarian, with a protective collar to prevent further damage.

Reason Four: Foreign Objects in the Eye

Objects like sand or glass can cause pain and prevent cats from fully closing their eyes. Untreated foreign bodies may lead to infection or blindness. Superficial objects can be flushed, but deeper penetration may require veterinary removal or surgery.

Reason Five: Dry Eye

Dry eye, or keratoconjunctivitis sicca (KCS), occurs when cats cannot produce enough tears to lubricate their eyes. Causes include weakened immune system, herpes virus infection, misuse of medications, or inner ear infections affecting nerves. Symptoms may include redness, squinting, dull eyes, or yellow discharge. Some cats sleep with eyes open to reduce discomfort.

Reason Six: Watching Their Owner

Some cats are very attached to their owners and cannot bear separation. They may sleep with eyes open to keep track of their owner’s movements, waking and following them if needed. Cats raised with close bonding feel secure and may be more attentive in this way.

Reason Seven: Waiting for Food

Hungry cats tend to be alert and sleep lightly to conserve energy. If they know food is nearby or mealtime is approaching, they may appear to sleep but keep watch, ready to respond quickly.

About the Third Eyelid

When cats sleep with eyes open, the third eyelid may be visible, sometimes making the cat appear to roll its eyes. The third eyelid, or nictitating membrane, is located at the inner corner of the eye. Each blink clears debris like dust and pollen. It also protects the eye from bright light.

During rest, the third eyelid becomes more noticeable to protect the cornea and keep the eye moist. However, if it is persistently visible, it may indicate eye irritation or other health issues. Cats may scratch at the eyes, which can worsen infections or injuries. Serious problems include conjunctivitis, corneal damage, ulcers, or even vision loss.

Causes of third eyelid protrusion include viral infections, parasites, or trauma. Timely veterinary evaluation is recommended to diagnose and treat the issue.