YOUR HORSE’S SLEEP CYCLE – FUN FACTS

Text: Rhiannon Cecil

We all know so much about our horses; what they should and shouldn’t eat, how much water they need, how to care for their bones, muscles, and tendons, and how to identify signs of colic. But how much do we really know about how they sleep?

Horses are checked at night and periodically throughout the day to make sure they are healthy and have enough roughage and water, but most of us don’t consider whether or not they’re getting enough sleep or even how much sleep they need. As human beings, we understand that if we don’t get enough sleep or go through a proper sleep cycle, we’re likely to be grumpy and disoriented throughout the next day. The same thing applies to horses. Here are some interesting insights into the sleep cycle of a horse.

1. Horses need fewer hours of sleep than humans

A human adult needs a minimum of seven hours of sleep to function optimally. Horses can survive much less, needing only three out of every twenty-four hours.

2. Horse sleeping patterns change depending on their age

Just like human babies, foals sleep more than adult horses do. A foal under three months old will spend around half his day sleeping, a lot of which is done lying down. As the foal grows, he’ll lie down and nap less and less.

Adult horses spend the majority of their day resting, eating, and sleeping. They can slip into a deep nap while standing up, but they can’t complete their full sleep cycle without lying down, which generally happens in the early hours of the morning. They can go from standing sleep to being fully alert very quickly, assuring they are safe from would-be predators during the day.

Senior horses are likely to nap more regularly, just like senior people.

3. How do horses sleep standing up?

‘Stay apparatus’ is the answer to this one. Horses have a unique anatomical mechanism known as the ‘stay apparatus’, which allows them to dislocate their knee and lock the joint while sleeping. This means they hardly have to use any muscles to keep themselves upright while they sleep. Horses sleep with both front legs straight and locked and generally alternate resting their hind legs throughout their standing sleep.

4. Horses have three sleep phases

The first phase is known as the ‘restfulness phase’. This is like a small catnap or light sleep for a human. Though the horse is napping, he can quickly wake up again if he needs to. The next phase is known as slow wave sleep and differs from the restfulness phase as it is a deeper sleep with an even more relaxed muscle tone. Both of these phases occur while the horse is standing.

Rapid eye movement sleep (REM sleep) is the deepest sleep cycle phase and occurs when the horse’s muscles are completely relaxed. For this, the horse has to be lying down.

5. Horses can’t achieve a full sleep cycle unless they lie down

While standing sleep is restful, and horses’ REM sleep requirements are minimal, a horse cannot enter REM sleep while standing up. All the skeletal muscles need to be completely relaxed for a horse to enter the REM stage, and this can only be achieved if they’re comfortable enough in their space to lie down. Horses actually wake up for a short period before entering REM sleep to double-check their environment is secure. If they feel they can’t lie down, over time, they’ll start suffering from sleep deprivation, which can lead to behavioural and performance problems.

Make sure your horse has a space in which he feels secure enough to lie down and that he has enough space to lie down and get back up comfortably. On average, a secure and comfortable horse will lie down to sleep two or three times a night.

6. Herd dynamics and natural sleep

While we provide safe environments for our horses, their natural instincts still govern their sleeping habits. As prey animals with minimal natural defence mechanisms – speed and their hind legs – they need to be able to gallop away from danger at any moment. For this reason, they need less sleep and only nap for short periods during the day to keep an eye on their surroundings.

Herd animals like horses rely heavily on the ‘safety in numbers’ principle, and when they are comfortable in paddocks, you’re likely to see them ‘sunbathing.’ Horses generally sunbathe communally, so you might find a few lying on their sides during the day, soaking up those rays. One or two horses will remain standing during these periods. They act as sentries for the other members of the herd.

How to improve your horse’s sleep

There is surprisingly little research on equine sleep cycles, but there are some signs to look for and ways to improve your horse’s sleep cycle.

1. Eliminate pain as a cause of lack of sleep

Older horses often battle to lie down due to joint pain, and general joint pain issues are also a consideration. If you haven’t seen your horse roll lately or he doesn’t lie down, it may be worth consulting a veterinarian and assessing his joints, as pain management protocols can massive improve sleep quality for horses in pain. 

2. Make sure the floor is comfortable

With no muscle below the knees and hocks, horses need a soft and comfortable surface to get into a sleeping position at night. Make sure your horse has a thick, clean bed of straw or shavings to lie down in.

3. Eliminate stress and anxiety

Is your horse’s sleep environment safe, calm, and quiet? If your horse is anxious or experiencing high levels of stress, he will protect himself by staying in a standing position. Be sure to eliminate excess noise and light, so he feels safe enough to lie down.

Changes in the environment, such as moving stable yards or attending away shows, can also boost anxiety levels, and lack of sleep may be the cause of poor show performance in some horses. Acclimatise your horse to as many different environments as possible to make sure changes don’t send him into a flat panic.

4. Look out for general grumpiness and behaviour changes

There are millions of reasons for a horse to act grumpier than usual or generally out of character, the most common of which is pain. If pain is not the cause, and has been eliminated as a potential cause of the personality change by a vet, lack of sleep could be the culprit. You may want to look at installing cameras in his stable so you can ascertain whether or not he is lying down and going into the REM stage of his sleep cycle at night.

Take home message

Knowing more about what your horse needs to perform to the best of his ability includes paying attention to and understanding his sleep cycle. This is key for both optimal performance and improved horse welfare. We aren’t at our happiest or most impressive when exhausted, and neither is your horse. Look out for the signs mentioned above, and make any changes you can to help your horse get a good night’s kip.