Can Horses Sleep Standing Up? How Horses Really Rest

How do horses sleep standing up?

The trick lies in a system of muscles, tendons and ligaments known as the stay apparatus. In the front legs, it braces the joints so the leg stays straight with very little muscle effort. In the hind legs, the horse can hook the kneecap over a ridge at the end of the thigh bone, which locks the stifle joint (the horse’s equivalent of our knee) and, through linked tendons, the hock below it.

Standing in this way, a horse usually rests one hind leg at a time, tipping that hoof on its toe while the other hind leg is locked. Its head drops, the lower lip may go slack, the ears relax sideways and the eyes half-close or shut. Every so often it shifts its weight and swaps legs.

Cows, deer and many other hoofed animals cannot lock their legs as completely, which is why the horse is the classic example of a mammal that naps on its feet.

Why do horses doze standing up?

Horses evolved on open grasslands where wolves, big cats and other predators could appear at any time. A large animal on long legs needs a few seconds to get up from the ground, and those seconds can matter. Resting on its feet lets a horse stay ready to bolt the moment it senses danger.

Horses also sleep more safely in groups. In a herd, it is common to see some horses lying down while one or more stand nearby, apparently on watch. A horse kept on its own often sleeps poorly and may rarely lie down, because it has nobody to keep guard.

Do horses need to lie down to sleep?

Yes. Light sleep and slow-wave sleep can happen standing up, but REM sleep, the stage in which the muscles go slack and the eyes flicker, needs the horse to lie down. If it tried to enter REM while standing, its muscles would relax so much that it could stumble or fall.

Horses lie down in two ways:

• Sternal position: lying upright on the chest and belly with the legs folded underneath, sometimes with the muzzle resting on the ground. Horses rest and sleep lightly like this.
• Lateral position: lying flat out on one side with the legs stretched. This is when most REM sleep happens.

Equine sleep researchers report that adult horses usually spend a fairly short time lying down each day, often less than a few hours in total, and that REM sleep makes up only a small part of it. When horses are prevented from lying down for days, for example because of an unfamiliar stable, stress or pain, they can become sleep deprived. Such horses sometimes buckle at the knees or even collapse while dozing upright, a sign that they need to lie down and sleep properly.

How much do horses sleep?

Horses sleep much less than people. Studies of adult horses give an average of roughly 2.5 to 3 hours of actual sleep per 24 hours, broken into many short episodes, often around 15 minutes each, rather than one long night’s sleep. Horses also spend several more hours each day simply resting or dozing on their feet, with estimates ranging from about 4 to 15 hours depending on the horse and its surroundings.

Most sleep happens at night and in the early hours of the morning, but horses also nap during the day, especially in warm sunshine after feeding. Grazing animals in general sleep little: cattle and sheep sleep only a few hours a day, while predators such as lions sleep much more.

How do foals sleep?

Foals sleep far more than adult horses and lie down much more often. In their first weeks, they spend a large part of each day stretched out flat on the ground, sleeping deeply near their mother while she grazes or stands guard. People seeing a foal lying motionless in a field for the first time are often alarmed, but this is perfectly normal.

As foals grow, they gradually spend more time on their feet and less time asleep. By the time they are yearlings, their sleep pattern looks much more like that of an adult horse.

Myths and facts about horse sleep

Myth: horses never lie down. Healthy horses lie down every day, and some lie flat out in the sun for long periods. They simply do not stay down for hours at a stretch the way people do.

Myth: a horse lying down is always sick. A horse lying quietly, especially in company and in good weather, is usually just resting. Owners learn what is normal for each horse.

Fact: horses can sleep with their eyes open. In light sleep, a horse’s eyes may stay partly open, which can make it hard to tell if a standing horse is awake or asleep.

Fact: other animals sleep in unusual ways too. Dolphins rest one half of the brain at a time, as explained in How do dolphins sleep?, and sloths were long thought to sleep far more than they do, as shown in How long do sloths sleep?.