Sleep is important, also for horses. But how do horses sleep? Have you ever seen your horse standing with its eyes closed and wondered if he was asleep? Quite likely, because horses can sleep standing up! Some, however, like us, also like to sleep lying down. Read more about “How do horses sleep?” in this article.
The different sleep phases of a horse
Not all sleep is the same. Horses have three different sleep phases: light dozing, light sleep phase (SWS) and deep sleep phase (also called REM sleep).
While dozing, horses are neither really awake nor really asleep. They are in a kind of preliminary stage to light sleep. They are still aware of everything in their environment but appear absent. This phase cannot be immediately distinguished from light sleep. This usually happens while standing with the eyes half-closed and the neck slightly lowered. One hind leg is resting.
Light sleep phase (SWS)
The abbreviation SWS stands for Slow Wave Sleep. The breathing rate and heartbeat slow down. Sometimes their muscles twitch a little. The brain is inactive. They lower their head a little and close their eyes. The hind legs are rested alternately. Again, they are aware of their surroundings, hear even the softest sounds and immediately wake up.
If horses lie on their chest, they are probably in a light sleep. In this position, the legs are bent and the head is carried. As soon as there is any sign of danger, they can get up quickly and flee.
Deep sleep phase (REM sleep)
The deep sleep phase is often considered to be the same as REM sleep, but deep sleep is a slight precursor to REM sleep. In the REM sleep phase, circulation and respiration are slowed down. The muscles are completely relaxed. The brain, however, is very active.
The abbreviation REM stands for Rapid Eye Movement, because in this phase the eyes are closed, but they twitch. It can be compared to the REM sleep phase in humans. Horses are only in REM sleep when they lie on their side and put their head on the ground. Deep sleep, on the other hand, is also possible when standing.
Standing or lying – In which position do horses sleep?
As with the sleep phases, there are three different sleeping positions: Standing, on the side or in chest/belly position. Usually, the position also reveals the sleeping phase, because the deeper the horse sleeps, the more the muscles relax. Despite all this, short deep sleep phases are also possible while standing.
Why can horses sleep standing up?
Odd, but true: horses sleep standing up. Though some might think they could fall over at the slightest gust of wind, this is not the case. A special equine characteristic, the so-called “stay apparatus” of the hindquarters makes it possible.
Here, two tendon cords ensure a coupling of the knee and hock joints. Now the horse blocks his kneecap by a short muscle contraction and thereby also immobilises the hock joint. His weight then rests mainly on this leg, while the other is relaxed and rests on the toe. The standing leg is switched about every 10 minutes.
This mechanism serves to ensure that the horses can flee as quickly as possible in case of danger, despite being asleep. This is also an advantage for older horses, as they often have joint problems and can no longer get up so easily. This way they can rest while standing.
Nice to know: The position where the head is supported on the ground is the most popular!
When do horses lie down to sleep?
Horses lie either on their chest or their side. In the chest position, horses have the option of holding their head themselves or resting it on the ground.
However, they only lie down when they feel safe. Horses are flight animals, which is why they are alert at all times. For example, if horses are resting on their sides, it takes them a while to get up and run away from danger. In the wild, these are vital seconds that matter. Therefore, your horse will only lie down to sleep when there is no danger.
Sleep duration – How long do horses sleep?
The length of sleep required depends entirely on age. Foals need significantly more sleep to recuperate than adult horses.
The sleeping behaviour of horses is different from that of humans. Basically, adult horses only sleep between three and five hours a day — and not all at once. Horses are stage sleepers and professionals at power napping. They sleep throughout the day and also at night in short intervals of up to 20 minutes. In addition, they doze for about 3 hours per day.
Can horses dream?
First things first: YES, it is believed that horses can indeed dream. However, they can only do this in the REM sleep phase. This is also called dream sleep. During this phase, the brain is very active. This is expressed by the small movements of the eyes. The brain waves measured by researchers are similar to those of humans, which is why it is assumed that horses can also dream.
Poor sleep and lack of sleep causes stress
Who can’t relate? One night of bad sleep and the day is a mess. It is the same with horses. If they do not get enough rest and are repeatedly disturbed during the different sleep phases, the body becomes stressed. Symptoms of sleep deprivation are, for example, reduced performance and behavioural disorders. Especially the athletes among the horses need enough restful sleep to stay healthy and perform well.
Good surface for good sleep – What owners can do
Sleep is especially important. Therefore, horses’ different habits should be taken into account. Horses prefer to sleep on a dry and clean surface. In the stable, straw is the best solution for a cosy bed, according to a Polish study from 2016. Sufficient bedding should be provided, so that the horse does not have to lie on hard, cold ground.
But not only the condition of the ground is important. When kept in an open stable or on pasture, enough space must be provided so that each horse can lie down. With a large herd of ten horses or more, this is of course more difficult than with a group of three. Care should be taken to provide enough space, so that even lower ranking animals can rest.