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How Do Horses Sleep?

 
By Ameera Mills. Updated: November 20, 2018
How Do Horses Sleep?

Like most herbivorous mammals, horses are not characterized for spending long periods of time sleeping. But a horse’s basis of sleep and a horse’s sleep characteristics are important to know for any horse lover. Like with all animals, good rest is essential for the proper development and maintenance of a horse’s body. A horse that is deprived of sleep and care could become ill and very likely die.

If you are wondering how much sleep horses needs and are curious about a horse’s sleep pattern, you’ve come to the right place. Here at AnimalWised we will be answering the commonly asked question, how do horses sleep? Keep reading to find out!

You may also be interested in: Do Rabbits Sleep?

The physiology of sleep in horses

In the past, sleep was considered as a "state of consciousness". Sleep was defined specifically as a period of immobility in which individuals did not respond to stimuli. Therefore, sleep was not treated as a behavior, nor part of the ethology of a species. Do not confuse resting with sleeping, as an animal can be resting without being asleep.

When studying sleep in horses, one uses the same methodology that is used with humans. Three parameters are measured; electroencephalogram to measure brain activity, electrooculogram for eye movement and electromyogram for muscle tension.

There are two types of sleep stages; slow wave or non-REM sleep and fast wave or REM sleep.

Non-REM sleep is characterized by slow brain waves and has 4 phases that are interspersed during the night. The 4 stages of non-REM sleep include:

  • Phase 1 or numbness: This is the first phase of sleep and does not only occur when an animal begins to fall asleep. Phase 1 of non-REM sleep can occur throughout the night, depending on the depth of a horse’s sleep. This sleep phase is characterized by waves (alpha) in the brain. In this phase of sleep even the smallest of noises can awaken an animal. During this sleep phase there still remains a record of muscular activity in a horse and their eyes begin to turn downwards.
  • Phase 2 or light sleep: In phase 2 of non-REM sleep, a horse’s sleep will deepen and their brain functioning in addition to muscular activity, will decrease. Theta waves which are slower than alphas will appear in this sleep phase. We then see the occurrence of K complexes sleep spindles (2 types of brainwaves) These complexes are similar to a kind of radar which allows our brain to detect any movement around us while we sleep. They also wake us up if any danger is detected.
  • Phase 3 and 4, delta or deep sleep: In these sleep phases, delta waves otherwise known as slow waves predominate. Brain activity is reduced but muscle tone increases. This is the phase where a body truly rests. It is also the phase where night terrors or sleepwalking occurs.

Fast wave sleep or REM sleep: the most characteristic pattern of this phase are rapid eye movements. In addition, muscular atonia occurs from the neck down. Muscular atonia means that the skeletal muscles completely relax and brain activity decreases. It is thought that this phase serves to consolidate memories and learning that occurred during the day. In addition, this phase is very important in animals, like horses, as it aids in brain development.

Why do horses sleep standing up?

As with other animals, routine changes or stress can interrupt the natural course of the horse's sleep patterns. If a horse’s routine is interrupted, it can also have consequences in a horse’s day-to-day life.

A horse can sleep standing up or a horse can sleep lying down. However, a horse can only enter REM sleep when it sleeps lying down. This is because, as we mentioned before, this phase is characterized by REM atonia from the neck down. This means that if a horse falls into REM sleep while standing up, it would fall.

Horses, like other animals that sleep on their feet, are prey animals. By this we mean that, throughout evolution, they have had to survive in a predator-full environment and always be aware of their surroundings. When a horse sleeps laying down it is becomes more helpless than when standing up. This is why, through a horse’s evolutionary process, they now sleep standing up in order to have a quicker reaction rate.

But how long do horses sleep? Due to this evolutionary process, horses don’t sleep very much. In fact, horses usually sleep less than three hours in a row.

How Do Horses Sleep? - Why do horses sleep standing up?

Horse care: Horse stable design

A horse’s stall should not be less than 3.5 x 3 square meters and should have a height greater than 2.3 meters. A horse’s stable requires bedding material, allowing a horse to rest properly.

A horse’s stall should also always have the appropriate amount of straw. Although, some equine hospitals (Horse clinic) prefer to use other inedible, dust-free and more absorbent materials to cover a horse stable floor. This is because, in certain situations (depending on your horse), consuming large amounts of straw can cause colic. In addition, if your horse is suffering from any respiratory problems, straw is not recommended. If you notice that your horse is suddenly suffering from any respiratory problems and lives among hay, consult your veterinarian.

If your horse lives and sleeps in a stable, be careful of weaving, which isone of the most common vices of horses in stables in boxes. For more, take a look at; Weaving In Horses.

How Do Horses Sleep? - Horse care: Horse stable design

Environmental enrichment for horses

If both the physical and health conditions of a horse allow it, he/she should not spend too many hours inside the stable. Walking and herding is a necessary source of enriches for a horse. Exercise for horses also helps in reducing the possibility of unwanted behaviors, such as; stereotypic behavior in horses. In addition, daily exercise for a horse is necessary in favoring healthy digestion.

Another way in which you can enrich a horse’s environment or resting area, is by providing your horse with toys. If your horse’s stable is large enough, you can play ball with your horse. Another alternative is to hang a ball from the ceiling, which your horse can play with by itself.

And remember your horse requires a calm environment with the right temperature, deprived of acoustic or visual stress.

For more on horse care, we suggest taking a look at our following articles;

How Do Horses Sleep? - Environmental enrichment for horses

If you want to read similar articles to How Do Horses Sleep?, we recommend you visit our Facts about the animal kingdom category.

Bibliography
  • Clarke, A. 2017. Environmental enrichment for the resting horse. Equine Health, 34: 1 – 4.
  • Dallaire, A. 1986. Rest Behavior. Veterinary Clinics of North America, 2 (3): 591 – 607.
  • GuíaSalud. 2015. Anexo 1. Fisiología del sueño. Características del sueño. Disponible en: http://www.guiasalud.es/egpc/TSue%C3%B1o_infado/resumida/documentos/anexos/anexo1.pdf
  • Pedersen, G. R., Søndergaard, E., and Ladewig, J. 2004. The Influence of Bedding on the Time Horses Spend Recumbent. Scientific Papers, 24 (4): 153 – 158.

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