There is much scrutiny when it comes to a horse's sleep routine. Do they always sleep standing up? Do they ever lie down? These are some of the most common questions that people ask about these large animals. If you're a new horse owner, you may find that your pet has strange sleeping habits, but there's usually no reason to be concerned. Understanding the horse's history in the wild can help owners to better understand their sleeping habits. 

Standing Up

Unlike humans or any other house pet, horses get very little REM sleep every day. Horses first lived in the open plains where their fight-or-flight instinct needed to be strong to escape predators. As a result, sleeping while standing up allows them to flee quickly when danger is sensed. Over time, the anatomy of the horse has changed to a point where their limbs, muscles and ligaments are able to "lock" in place, allowing a horse to sleep while standing up. This is referred to as a "stay apparatus". Horses sleep in different cycles. While standing, they can doze off and experience Slow Wave Sleep (SWS), but they also need Rapid Eye Movement (REM) sleep, which only occurs while they are lying down. 

Lying Down

Many horses prefer to sleep lying down than standing up simply because it's more comfortable. As mentioned above, horses are only able to engage in REM while lying down. Most experts say horses need anywhere from 30 minutes to 3 hours a day in the REM stage. Horses must be fully lying down on their side. You may even catch their legs moving, which means you are watching the horse have a dream. Because horses are very large animals, they can only lie down for about 45 minutes at time. Their weight can cause excess pressure on their internal organs. It is not uncommon to see a pasture of horses with many of them lying down, and at least one standing up. The standing horse is keeping watch over the others and keeping an eye on potential predators or other signs of danger. 

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Sleep Patterns 

A horse's sleep pattern varies and depends on their environment. As humans, we sleep continuously for hours, while a horse breaks up its sleep over a 24-hour period. They may snooze for a few minutes while standing up, or lie down for a few hours in the sun to get REM sleep. They are notorious for surviving with minimal amounts of sleep. Over the course of a 24-hour time period, their minutes of sleep should add up to about 3 hours total. Foals will spend more time sleeping than adult horses.

Sources: Equestrian Co, Adelaide Edu