Sleep deprivation is common in horses. How do you recognise that your horse might be sleep deprived and what can you do about it?
Adequate sleep is a welfare issue, and a performance issue, but it's also a safety issue for you and people who handle your horses.
Horses sleep far less than humans. They sleep for about 3 hours throughout the day. Mostly these are small periods of sleep standing up, in which the horse engages their 'stay apparatus', and they usually have about 20 minutes of REM sleep in which they lie down.
Although the above pictures are not perfect, ideally the joints will 'stack' one below the other, allowing this engagement, and preventing the horse from falling over when they are asleep.
The stay apparatus is essential for the horse to sleep standing up. Many horses experiencing imbalances or pain may not be able to engage their stay apparatus and will be sleep deprived as a result. They start to sleep, and relax, but then their stay apparatus fails, and they almost fall, or do fall, so they wake up. This can result in a bunch of symptoms. One of which is grumpiness. They also often have scrapes or scars on the front of their fetlocks as a result of this joint buckling over when their stay apparatus fails.
Besides witnessing excessive daytime sleepiness in the horse, a clue that the horse may have a sleep disorder is the presence of abrasions or scars in the dorsal aspect of both fetlocks and carpi.
D. Colette Williams, BS; and Terrell Holliday, DVM, PhD,
A recent study found injury occurrence in more than 90 percent of the observed horses suffering from recumbent sleep deprivation, with the most common injuries found on the knees and fetlocks where they had dropped quickly to the floor as their legs buckled (Fuchs et al., 2019). Head injuries and hock injuries are also often seen in association with this condition (Fuchs et al., 2019).
It's important to be vigilant to pain or imbalances in your horses. Do they only bend one way? Do they have trouble picking up one lead in a canter? Do they stand over at the knee, or frequently weight and unweight different hooves? If you notice these symptoms in your horse it's important to consult a bodyworker who can identify the cause and hopefully adjust your horse.
If you have been travelling your horses to events, or they are experiencing other changes to their routine, herd changes, environment changes, it's natural that they will be more vigilant and sleep less.
Sleep deprivation is common in horses. Other sleep disorders may be less common, not recognized, or poorly understood. If a sleep disorder is suspected in a horse, documenting the events associated with the onset of such problems may be helpful. Note possible triggering events, if any, like environmental conditions, housing (stall versus outdoors), bedding, introduction of new horses, isolation, removal of a herd mate, wildlife in the area, traveling, horse’s behavior, painful conditions, medical problems, and the behaviors of other horses.
A recent study released in August 2022 - A Review of Equine Sleep' raises many issues of husbandry that may influence sleep deprivation in horses. Performance horses often travel and stay in unfamiliar environments away from their herd. As a prey animal, it's difficult for horses to relax enough to get adequate sleep without the presence of a ''sentinel horse'. If you keep your horses in a herd you will observe that when one or more horses in your herd sleep lying flat on the ground, another horse in the herd will stay upright and watch over them.
Horses rely on having a sentinel to stand watch over them when they sleep. As a prey species, this is an important safety factor and as a result, horses who are not in a stable herd of companions may find it difficult to feel safe enough to lie down to sleep. Horses who are repeatedly disturbed or pushed around by other horses may similarly feel too vulnerable to lie down, thus preventing them from achieving paradoxical sleep. The introduction of new horses or the removal of horses from a stable herd may disrupt the herd dynamics and have a negative effect on the amount of sleep the individuals are getting.
There are some methods of husbandry that involve introducing artificial light or other disturbances into a sleep space to disrupt circadian rhythms with the goal of achieving better quality coats, or delaying the onset of winter coats, or extending the breeding season for broodmares. If you have research supporting this method working to achieve these goals, please include them in the comments below. We have been unable to find concrete evidence that deliberately disrupting the sleep of horses had positive outcomes, but we are open to evidence.
Ideally, you will keep your horses in a space they are familiar with, including all their needs - adequate feed, fresh water, shelter, companionship with horses they get along with, freedom from pain, and a predictable routine. Under those circumstances horses should be able to achieve adequate sleep. This will improve performance, make them less grumpy, safer, but also improve the quality of their lives.
If you observe symptoms of sleep deprivation (such as your horse collapsing on your farrier), grumpiness, unexplained injuries, weight loss, lack of evidence of lying down - no grass, or dust or bedding on the coat, or hypervigilance, it's important to identify the reason your horse is sleep deprived. Sometimes it's a simple as being paddocked with a bully who won't let them chill. Consult with a bodyworker to make sure there are no physical obstructions to your horse having adequate rest.
A Review of Equine Sleep: Implications for Equine Welfare
Front. Vet. Sci., 17 August 2022
Sec. Animal Behavior and Welfare
Linda Greening1* and Sebastian McBride2
Qualitative and Quantitative Characteristics of the Electroencephalogram in Normal Horses during Spontaneous Drowsiness and Sleep
Williams, D.C., Aleman, M., Holliday, T.A., Fletcher, D.J., Tharp, B., Kass, P.H., Steffey, E.P. and LeCouteur, R.A. (2008), Journal of Veterinary Internal Medicine, 22: 630–638.
Sleep and Sleep Disorders in Horses Monica Aleman, MVZ, PhD, Diplomate ACVIM; D. Colette Williams, BS; and Terrell Holliday, DVM, PhD, Diplomate ACVIM 2008 Vol. 54 AAEP PROCEEDINGS
The characteristics of equine sleep January 1980
Authors Katherine A Houpt Cornell University
Sleep deprivation in horses Anna Haines
16 June 2022 Improve Veterinary Practice