How Do Horses Sleep?

Last updated: March 29, 2019

Overview

Just like with other animals, sleeping is also important to horses. Being in a state of deep sleep is ensures that horses function properly, both mentally and physically. This is crucial for horses because they are beasts of burden. Some horses function as farmhands. They spend the day lugging heavy produce and farm equipment. Farmers also use them to pull carts or as a means of transportation. Some horses are bred to be racehorses.

All of these activities take their toll on the minds and bodies of horses. Imagine how tired you would be if you spent your day racing with others, with someone riding on your back. Sleep ensures that their bodies recover and heal themselves.

We’ve all seen horses always portrayed as animals that sleep standing up. Whenever they show a horse sleeping in a movie, the horse is always standing up. This is why it is not surprising that we all have this mental image of a horse standing up, eyes closed, dreaming of running freely in the open plains.

This is a common misconception. Horses don’t sleep standing up. Horses snooze standing up. What’s the difference? Aren’t they the same thing?

Why do horses sleep standing up?

When you see a horse standing still with its eyes closed, it’s not sleeping. It is dozing. Dozing is light sleeping. And horses spend a lot of time dozing. Want some proof? Drive by a ranch or a pasture with horses and count how many of those horses are active. Check how many of them are grazing and how many are walking or running around. Now, check how many of them are just standing with their heads down and their eyes closed.

Horses can get some light sleep without having to lay down. This is due to a special mechanism in the equine anatomy. This mechanism is the Stay Apparatus. A horse can lock its kneecap with ligaments and tendons to keep its joints aligned. All while standing perfectly still. As a result, the horse’s bones get locked together.

Sleeping on one’s feet is uncomfortable for humans. This is not the case for horses. For horses, lying down is more uncomfortable. Due to their large sizes, their blood flow might be restricted if they lie down for long periods. It can result in excessive pressure on their internal organs.

The Stay Apparatus is a product of evolution and a means of survival for horses. Before humans learned how to domesticate horses, they are wild animals. And for them to survive in the wild, they need to always be ready to outrun their predators at a moment’s notice.

A quick escape from an attack by a predator won’t be possible if they sleep lying down. They will waste precious seconds if they have to get up every time they get attacked while sleeping. And in the world of predators and preys, those few seconds can mean the difference between life and death. Even now when most horses are stabled, this survival technique has been forever embedded in their genetic makeup.

Do horses experience REM Sleep?

Horses, just like humans, also experience REM Sleep. For horses to achieve REM Sleep, they need to lie down. But unlike humans, horses don’t require a lot of REM sleep. Horses usually need roughly 2 to 3 hours of REM sleep a night. And these 2 or 3 hours are not continuous. Horses sleep deeply in short bursts of 10 to 20 minutes a time.

Sleeping in a safe environment

There is another requirement for a horse to lie down to sleep. Unlike humans who just lie down whenever they feel sleepy, horses need a sense of security before they do so. Lying down can be a very dangerous maneuver if you live in an environment where you can be a predator’s dinner in an instant. This kind of environmental stressor is not limited to just wild horses.

Even domesticated horses need a safe environment before they decide to lie down. Even with the absence of wolves or other predators, a horse in a ranch or in a stall won’t lay down if it experiences stress.

Horses use the buddy system for sleeping. When one horse is sleeping, the other stays awake to watch over. It’s the same system that humans do when they go on trips or hikes. The buddy system is meant to ensure that someone’s got your back and always on the lookout for possible danger. When the sleeping horse wakes up, the watch-horse will take its place and the other will be the new watch-horse. This arrangement or rotation is not just for horses in barns. A group of horses or a herd of horses will also exhibit the same pattern.

Even though they don’t have any predators in ranches or farm pastures, there are still problems affecting the hours of sleep that a modern horse will have. A loud and busy barn can disrupt a horse’s sleep. Another common issue is the size of the stall where the horse sleeps. If the stall is too small, the horse won’t be comfortable enough to lie down and sleep.

What are the normal sleep patterns of horses?

Studies conducted in from the 1960s to the ’70s showed that horses have four phases of sleep. These are diffuse drowsiness, intermediary, slow-wave, and paradoxical.

Diffuse drowsiness is light sleep. This is when a horse stands with its front legs parallel. It has a slightly lowered head and neck. It is also common for the horse to display a downward gaze with relaxed eyelids, ears, and lower lip. During this stage, you might notice the horse resting one of its hind legs. While the horse rests one hind leg, the hind-end weight gets support or carried by the other rear limb.

The Intermediary Phase is the phase just before the horse lies down. This is the part where the horse is alert. It takes its time examining the surroundings. If satisfied that there is no immediate threat, it lies down. Once lying down, the horse will go through the diffuse drowsiness state again.

A horse will only go through the Slow-Wave phase if it is confident about the safety of its environment. A drowsy horse often lies in sternal recumbency. This means that the horse is on its abdomen and its legs tucked under. In this stage of sleep, a horse often has its head slightly raised. Up to this point, the horse can get easily aroused from its slight slumber. Horses, in general, lie on their side when they want to move into slow-wave sleep.

In paradoxical sleep, the horse needs to lie down. This is so all of its muscles can relax. This is the phase where REM occurs. And although this is the stage of deep sleep, a horse’s brain is still very active. What’s interesting about this is that although the brain is active, the horse is in a paralyzed state. If you see a horse in paradoxical sleep, you will notice that it moves its head to the side and to the ground. The horse does this so its head can remain propped up. There have been suggestions that horses favor this sternal posture. The most likely reason for this preference is horses have an easier time breathing in this position than when they are lying on their sides.

Why is REM Sleep important for horses?

Rapid Eye Movement or REM Sleep is the most important stage in the sleep cycle. It is particularly important for developing the nervous system. This is also the stage where new memories get created.

Studies have shown that even if an animal is allowed to sleep uninterrupted if they get constantly woken up from REM sleep, they will have a reduced ability to learn.

When a horse is sleep-deprived, it becomes week. It also loses the ability to control its body temperature. Its metabolism exhilarates. When this happens, it will require more food than normal, yet it will still lose weight.

The same thing happens to humans. Humans who experience sleep-deprivation often suffer from discomfort or drowsiness. The lack of REM sleep results in a change of activity of neurotransmitters and the central nervous system. As a result, it negatively impacts the wellbeing. The ability to learn and store new memories are also affected.

What are the reasons why a horse won’t or cannot lie down to sleep?

Pain. If a horse associates lying down to pain, then it will not voluntarily do so. If a horse experiences musculoskeletal pain, a horse might resist the notion of lying down. Examples of this kind of pain include osteoarthritis, abdominal, or thoracic pain.

Dominance displacement. Some horses, particularly geldings, take the role of the dominant horse in a group. This is similar to the Alpha male of wolf packs. There is a theory that these horses do not sleep because they feel that it is their responsibility to keep vigil over the herd. This condition is often found when there is no alpha male in the herd.

Sleep Terrors. Some horses experience sleep terrors, just like humans. You will them lying on their sides with their legs moving as if they are running. They then suddenly rise in confusion and fear. They often remain in this agitated state for a few minutes.

What can be done help a horse get more sleep?

There are several techniques that one can employ to provide a horse with a feeling of security.

The first one is to add a companion horse. This is a technique that works not just for horses that live on farm pastures. This will also work for horses that sleep on barn stalls or paddocks. Even if the horse cannot see its companion, it can sense that it is not alone in the paddock. This is enough to make the horse feel more secure.

Horse owners can also remove an aggressive horse from an area. Aggressive horses can disrupt the harmony in a group. They can also intimidate “weaker” horses. When this happens, the other horses will always be on guard and end up being sleep-deprived. They will display behavior similar to when a predator is on the hunt for them. As a result, they will forego deep sleep so that they can quickly escape from the aggressive horse.

An increase in the size of the stall or paddock can also help a horse get more sleep. As mentioned earlier, horses need enough room for them to lie down and sleep comfortably. If a horse can stretch properly while sleeping, they can get into a deep sleep in a shorter time.

Horse owners can also move a horse away from loud noises. The loud sound generated by highways or traffic can agitate a horse. In the same way that humans have a hard time sleeping when there are loud outside noises, horses also need a quiet place to sleep.

Humans are fortunate enough to have noise-dampening curtains or white noise machines. They can use these devices to block out loud disruptive noises. These devices are not available to horses. The best thing that horse owners can do is to make sure that the paddock or shelter is far away from the source of loud noises. Even the constant humming generated by power lines can prevent horses from sleeping soundly.

What are the common sleeping habits of horses?

Horses usually lie down to dun themselves. You can even find several horses lying down at the same time. This is their version of a communal sunbath on a warm spring day. When in cold snowy conditions, horses tend to spend less time lying down.

The sleeping patterns of horses also change as they age. A young horse, a foal or a pony under three months of age, can sleep for up to 12 hours a day. On the other hand, older horses, sleep only for about 3 hours in an entire 24-hour period. Much older horses, sleep more but not as much as foals.

Additional Resources

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