Understanding How Horses Sleep Standing Up vs Laying Down

Snooze schedules and the stay apparatus.

Updated July 1, 2024

Just like for people, the amount and quality of sleep your horse gets each day is fundamental to their health and well-being. However, horses need far less sleep than humans to function and they may even rest while standing up.

We’ll explain what a normal sleep cycle is for horses, how much shuteye they need per day, and strategies you can use to help your horse get quality sleep.

Equine Sleep Patterns and Stages

While many people need continuous hours of uninterrupted, quality sleep each day, horses can have multiple periods of sleep throughout 24 hours. They are known as polyphasic sleepers who take short naps throughout the day with most of their sleep concentrated at night.

Sleep cycles can be broken down into four stages documented in horses, which include:

1. Wakefulness: A full sleep cycle includes periods where the horse is awakened.
2. Drowsiness or Light Sleep: Typically occurs just before NREM or REM sleep.
3. Non-Rapid Eye Movement (NREM): Also known as slow wave sleep, this is a state of deep rest where a horse’s brain waves significantly slow down. Horses can enter NREM sleep while standing up or lying down in sternal recumbency (with their legs tucked underneath them, but not fully flat out).
4. Rapid Eye Movement (REM): Characterized by quick, irregular brain waves that are similar to when a horse is awake, along with rapid back-and-forth eye movements. REM sleep can only take place when a horse is lying down on their side. Even though all their muscles become completely relaxed during this stage, you may see some twitches in the ears, skin, nostrils, eyelids, and legs.

How Much Sleep Does My Horse Need?

Adult horses generally need 5-7 hours of sleep per day. Most of this (over 75%) can be NREM sleep while standing up. However, horses need about 30 minutes of that time to be REM sleep which can only happen while lying down.

This relatively short amount of REM sleep is required every day. If your horse doesn’t have this, they may become sleep deprived, narcoleptic, or suffer other health consequences. Some horses are able to delay when they get REM sleep for several days without serious health effects, however, classic signs of sleep deprivation (like collapsing) may begin to show.

Why Do Horses Sleep Standing Up?

Horses are prey animals and sleeping standing up is one way in which they’ve adapted to the threat of predators. This survival mechanism allows them to remain somewhat alert and ready to quickly flee from predators without the delay and effort of getting up from the ground. Other equids, like donkeys and zebras, are also able to sleep standing up.

Another reason why horses sleep standing up has to do with their large body size and weight. Lying down for too long can interfere with blood flow and their substantial weight can put stress on internal organs and nerves.

Although, adult horses do sleep lying down, they only do so for short periods (typically less than an hour). Young horses and foals can sleep lying down for longer periods, but they also weigh far less.

Understanding the Stay Apparatus

You may be wondering how horses can get some sleep on all four legs without toppling over. Well, they have a special system of tendons and ligaments that stabilize the major joints in their legs called the stay apparatus. These soft tissues stabilize the joints in the forelimb and hindlimb, allowing horses to doze while standing with little effort.

Ensuring Your Horse Gets Quality Sleep Time

As an owner or caretaker, there are several factors that influence if your horse can snooze in peace.

Environmental Factors

Make sure your horse has enough room to comfortably lie down, whether that be the size of the stall, run in, or paddock. Also consider the quality and comfort of the bedding you’re using. One study showed that horses are more likely to sleep when they have access to a soft, thick bedded and adequately sized area suitable for lying down [2].

Another factor is how familiar your horse is with their surroundings. Many horses require a period to acclimate to a new barn or paddock before feeling safe enough to lie down and sleep.

Lastly, artificial light can affect circadian rhythms. A study examining the effects of overnight light on sleep behavior showed horses spent less time in recumbent sleep (NREM and REM) [3]. So be sure to turn off the lights every night and during the day when not necessary. You may also find success with using specially designed masks that block blue light to help support the natural production of melatonin, and therefore restful sleep.

Herd Mentality

Horses naturally belong in a herd and the absence of that social dynamic can affect their sleep. A herd – whether in the wild, out to pasture, or seeing each other through stall dividers – may have some horses lying down sleeping or resting while one or two others are standing, essentially keeping guard in case there is danger (predators). If your horse is the only equine or animal on the property, they don’t have anyone standing guard for them while sleeping, and this can cause them to be sleep deprived.

Physical Discomfort

Conditions that cause pain, like arthritis or laminitis, may prevent a horse from lying down, due to the potential effort and discomfort of standing back up. Many senior horses with joint discomfort will avoid lying down for this reason, and therefore, become deprived of REM sleep.

In this case, it may be smart to call your veterinarian so they can examine your horse and diagnose any pain or discomfort. They may be able to prescribe medications or discuss other treatments, including supplements, to address the source of discomfort.

More research needs to be done on other potential factors affecting sleep such as the horse’s emotional state, level of exercise, and nutrition.

Ask the Vet Video on Sleeping Habits for Horses

In this video, Dr. Lydia Gray describes the requirements for horses to have restful, complete sleep cycles and factors that may hinder this.

Evidence-Based References

1. Greening, Linda, and Sebastian McBride. “A Review of Equine Sleep: Implications for Equine Welfare.” Frontiers in veterinary science vol. 9 916737. 17 Aug. 2022, doi:10.3389/fvets.2022.916737
2. Luz, Marina P. F., et al. “Feeding time and agonistic behavior in horses: influence of distance, proportion, and height of troughs.” Journal of Equine Veterinary Science, vol. 35, no. 10, Oct. 2015, pp. 843-848.e1. https://doi.org/10.1016/j.jevs.2015.08.004.
3. Greening, Linda, et al. “The Effect of Altering Routine Husbandry Factors on Sleep Duration and Memory Consolidation in the Horse.” Applied Animal Behaviour Science, vol. 236, Mar. 2021, p. 105229. https://doi.org/10.1016/j.applanim.2021.105229.