Why Cats "Blep" in Their Sleep: The Surprising Reasons Revealed by Animal Experts

While it looks really cute and often goes viral on social media, a cat sleeping with its tongue out is usually just a byproduct of their unique anatomy. According to veterinary experts, including researchers from Cambridge University, the reason is far more mechanical than most owners realize.

Cats are crepuscular hunters who spend a vast portion of their lives resting, and their physical features are designed to facilitate this deep relaxation.

Why Do Cats Sleep With Their Tongue Out?

The most straightforward reason is simply that the cat’s front teeth are very small. Unlike humans, whose teeth and jaw structure naturally keep the tongue contained, a cat’s ones are tiny and don't always act as a barrier.

When a cat enters a deep state of sleep, their jaw muscles go completely limp. Because those front teeth are so little, they fail to "hold" the tongue in place, thus allowing it to slide forward and peak through the lips.

Apart from that, throughout the day, a cat uses its tongue constantly — for grooming, eating, and drinking. This requires continuous muscular tension. By the time evening rolls around, these muscles can become fatigued.

During deep sleep cycles, the cat’s body enters a phase of total muscle atony; in this state, the tongue relaxes entirely, often slipping out involuntarily as the animal "dissolves" into its rest.

Additionally, cats are evolutionary masters of the short rest, often sleeping in bursts rather than one long stretch. This habit allows them to stay vigilant against threats or ready for prey. However, when they do settle in for those longer periods — which can last up to 20 hours for kittens and seniors — their bodies prioritize recovery.

Seeing that little pink tongue is a visual cue that your cat’s nervous system has successfully switched from "hunter mode" to "recovery mode," indicating they trust their surroundings enough to let their guard down completely.