You may have heard that horses sleep standing up. That claim is only partly true, but the reality of horse sleep is just as fascinating. In this post, we dive into horses’ strange sleeping behaviour.
Stages of Horse Sleep
Besides wakefulness, horses have 3 stages in their sleep-wake cycle. In the state of drowsiness or deep restfulness, a horse is relaxed but still easily roused.
Next, the horse enters slow-wave sleep (SWS), in which its brain is less active, with slow, synchronized electrical waves. Horses stay standing for both deep restfulness and SWS.
However, the animal must lie down for the deep rapid-eye-movement (REM) sleep so that its skeletal muscles can relax. REM sleep is also known as paradoxical sleep because, counterintuitively, the horse’s brain is just as active as when it’s awake. As the name suggests, horses in REM sleep display jerky eye movements (with closed eyelids) and rapid, chaotic brain waves.
REM sleep is essential for horses’ well-being, as well as for learning and the creation of new memories. It’s likely that horses dream during this stage. They may move their legs while dreaming and probably dream about experiences from their day.
Horse Sleeping Behaviour
As prey animals, horses do most of their dozing standing up so that it’s easier to flee if a predator appears. Like several other large land mammals, they have a feature known as the stay apparatus, a system of tendons and ligaments that lets them lock their leg joints while sleeping.
When horses are sleeping, they distribute their weight among 3 of their legs and rest the fourth one, normally a hind limb. They also close their eyes, relax their ears, and droop their head, neck, and lower lip.
Before lying down, a horse wakes up for a moment to check its environment. It then lies down - likely on its side - and enters REM sleep via deep restfulness and SWS. It cannot lie down for too long since its weight restricts blood flow and puts pressure on its internal organs.
Among horses living in a group, 1 or 2 horses will typically stay awake while the rest of the herd lies down. These guard horses get their own chance to sleep when other horses replace them. Horses are careful to sleep in sheltered locations, preferably with their head pointing toward the escape route.
Horse Sleep Requirements and Issues
Horses sleep for only a few minutes at a time, alternating between dozing, lying down, eating, and moving around. Sleeping may occur during the day or night, although the nighttime is more common, especially among horses that work during the day.
On average, horses sleep only 3 hours total over a 24-hour period. At least 30 minutes of that sleeping should be REM sleep. Foals sleep for about half the day until they’re 3 months old, at which point they start sleeping less.
Although a horse can survive for several days without REM sleep, sleep deprivation can cause crankiness, issues with metabolism and body temperature, and even collapsing. Reasons that a horse might not get enough deep sleep include pain or discomfort at lying down and feeling uncomfortable in its environment.
Horses may also suffer from narcolepsy, a neurological condition in which they enter deep sleep frequently yet unintentionally. Horses with narcolepsy enter REM sleep nearly instantly, causing them to collapse.
Do you have a favourite fact about horses and sleep? Let us know in the comments!
Hello, My name is Shelby Gatti, and I am the owner of Shelby Ranch. I love being able to share my passion for animals with you and your family. At Shelby Ranch you can expect a ton of family adventure from horseback riding to mechanical bull riding & axe throwing.