Is your horse getting enough sleep?

Sleep is a topic that isn’t commonly discussed among horse owners, yet it’s an extremely important one to understand if we’re to provide our horses with the best possible quality of life. 

Anyone who has ever been deprived of sleep will know only too well how much impact it can have, affecting our attitudes, emotions and behaviour. 

Sleep is an essential part of every equine’s life, too, but the way in which horses sleep and the durations of their sleep periods are very different from our own. 

Sleeping arrangements

Horses are polyphasic sleepers, which means they take their sleep in multiple bouts spread throughout the day and night. They usually require between two and a half and five hours’ sleep in a 24-hour period. Foals and elderly horses sleep for longer than adult ones. 

While horses will sleep in the day as well as at night, the majority of sleep bouts are taken between 8pm and 5am, with most rapid eye movement (REM) sleep happening between midnight and 4am.

Five stages

There are five stages in this routine…

1. Alert wakefulness (being fully awake).
2. Diffuse drowsiness (the lightest stage of non-REM sleep).
3. Intermediate period.
4. Slow-wave sleep.
5. Paradoxical sleep, also referred to as REM sleep.

In the intermediate period the horse will briefly awaken while in the standing position to check the safety of his environment before lying down and entering a phase of slow-wave sleep. If he’s comfortable and confident in his environment, he will move into lateral recumbency and enter a phase of REM sleep.

Did you know? 

Although horses are able to achieve slow-wave sleep in a standing position, they cannot achieve REM sleep without lying down.

Flat out

To gain REM sleep, horses must be recumbent with the full weight of their head supported, or lying flat. When a horse is in REM sleep, there’s complete loss of muscle tone, so he’s unable to support himself in any way.

Brain activity during this sleep phase is extremely similar to when the horse is awake, hence the alternative term, paradoxical sleep. During REM sleep, movements and muscle twitches are often seen but these are caused by the brain stem. Heart and respiration rates may also increase and are often irregular.

Bursts of rapid eye movements occur, with the eyes darting from side to side, often accompanied by ear and facial twitching, limb movements and, occasionally, even vocalisation. 

Did you know?

REM sleep is essential because it’s when the brain rests and repairs itself, emotional experiences are processed and memories are consolidated. 

Sleep deprivation

Horses who choose not to lie down for any reason, or are physically unable to do so, can experience recumbent sleep deprivation, and this has a substantial impact on health and quality of life. It could cause the horse to fall into REM sleep while standing, which then causes him to collapse as a result of the complete loss of muscle tone, with a risk of significant injuries occurring. 

Identifying sleep deprivation in your horse is not always easy – often collapses will happen at quieter times of the day, or at night. If your horse is kept in an area with soft bedding or turned out full-time, there may be no visible injuries, but internal damage can occur.

You might notice a difference in his behaviour, such as being less affectionate towards you or his companions, or less tolerant of other horses. He might become more reactive or spookier than usual, or show signs of increased sensitivity to touch or sounds. However, these changes are sometimes subtle and not always easy to spot. 

If your horse is falling into REM sleep while standing, the most likely injuries you’ll see are knee and fetlock abrasions, unexplained head injuries and scratches or scrapes. Often, knee and fetlock abrasions will be recurrent, which is a tell-tale sign that sleep deprivation could be the cause. 

Because horses suffering from sleep deprivation often fully or partially collapse during the night, cases can remain undetected for months or even years. 

Did you know?

A horse with sleep deprivation who doesn’t lie down to sleep usually still rolls on a daily basis, so dirt or bedding on the coat isn’t necessarily confirmation he’s been lying down to sleep.

Possible causes

The primary cause for sleep deprivation in horses is pain or discomfort, so it’s essential your first port of call is your vet. It often requires extremely thorough veterinary investigations to get to the bottom of the cause, and, even then, it’s not always possible to identify or rectify the cause. 

There are several environmental stressors that can contribute to the development of sleep deprivation. These include…

• extreme temperatures
• lack of social contact
• unfamiliar surroundings
• lack of social stability
• inappropriate housing
• environmental noises 

As a prey species, horses rely heavily on their companions for safety, especially when sleeping. If they’re not in a consistent group or are kept with individuals who repeatedly disturb or push them around, they may not feel safe enough to lie down to sleep. 

The introduction of new horses or the removal of horses may disrupt the existing group dynamics and have a negative effect on the amount of sleep the individuals are getting.

Top tip

It isn’t recommended to start riding a horse as soon as he arrives in his new home, as several factors can cause this to be unsafe, sleep deprivation being just one.

Heightened risk

Hospital patients and horses taken to competitions with overnight stays may also be at risk of suffering from sleep deprivation due to the busy, stressful and unfamiliar environments they find themselves in. 

Changes of environment are stressful for horses, and when moving to a new yard, a horse might not sleep at all for the first few days, followed by reduced sleep for up to a month as he settles in. 

Sometimes, horses are housed in stables without enough space for them to comfortably and safely lie down. Although most sleep deprivation cases are challenging and complex to solve, some are easily sorted out by adjusting yard routine, social groups or stabling environment. 

Wise precautions

When a sleep disorder is suspected, ensure that the stable and any concrete areas are well padded, with rubber matting on the floors and walls, and that a thick bed is provided to help reduce the risk injury. Some horses may benefit from wearing padded boots on their forelegs to prevent recurrence of abrasions while further investigations take place.  

Take action

Although horses require significantly less sleep than humans, it’s still an essential part of their daily behavioural pattern. When sleep deprivation occurs due to environmental or anxiety-based factors, identification of the exact cause is vital to enable you to make the necessary alterations to your horse’s life. If sleeplessness is due to anxiety or fear, it may be necessary to speak to an equine veterinary behaviourist to consider the use of medication alongside a behavioural modification programme provided by an Animal Behaviour and Training Council clinical equine behaviourist. 

Did you know?

Horses who are unable to gain REM sleep may display an increase in the amount of slow-wave sleep, or dozing, that they do in an attempt to compensate for the missing restorative sleep. 

Watch and monitor

Ensuring your horse is able to get the sleep he needs is central to safeguarding his welfare. Filming him overnight can be an eye-opening exercise and even if he is having enough sleep, it will give you an insight into his time budget through the night. This useful knowledge will alert you to any need for management alterations, as well as highlighting any pain behaviour that may not be displayed during daytime hours.