Horses often sunbathe together for short periods, and while it makes us all panic — it’s perfectly normal behavior!

How much sleep does a horse need? Guess what – 3 to 5 hours in a 24-hour period is about average for a mature horse. Doesn’t that sound crazy? But it’s true. And as you probably know, horses also can sleep standing up; and can often go for days or even months without laying down to sleep. Horses are considered “cathemeral”; that is, they neither stay awake all day and sleep all night, or the opposite, but do a mixture of waking some hours during daylight, sleeping some daylight hours, and the same mixed pattern at night as well. They can go quite a while without sleep if forced but like all mammals need to rest eventually.

A horse’s physical body is large and he is a vulnerable animal to predators so nature made some things on the horse a little different for his survival. The most remarkable thing is the resting hind leg sling arrangement with the stifle that the horse can do. This has a purpose. It puts the hind leg in a cocked, ready-to-use position should a sudden emergency arise where the horse must kick an attacker, or run away from danger. When the horse rotates his hip (right, or left) in a standing position, he can put the hind leg in rest by using the ligaments that are arranged in a way that puts the leg at the top of the limb into a “sling”. Thus, he can stand on three legs and rest a fourth. He will relax his topline and his head will extend out from the neck, which lowers to allow comfortable breathing and the ears to be in line with both sides of the body, checking for anything moving near to the sensitive underparts, the flanks or elbows which are closest to vital organs. The lips will relax and sometimes the eyes will nearly close, or eyelids twitch while the lower lip hangs a bit limp. Yet, one sound or movement brings the head up, the eyes wide open and all four legs on the ground ready to dig in and take off.

When a horse is “recumbent”, or lays down flat, they are usually taking a short sunbath and will often stretch out the neck and close the eyes for no more than 15 to 30 minutes of deep sleep. During this sleep they will often appear to “snore” because the lungs are under some strain in this position. Young foals will often sleep flat on their sides for short periods (they usually sleep about half the day in total when they are very young), but this sort of sleep position tends to be used less and less as the horse ages. The horse is most vulnerable when off his feet, so horses that are worried, compromised for some reason or unhealthy will often not lay down. Remember –  a horse that is laying down isn’t all that comfortable especially when they are mature — and many horses get better rest when on their feet. When a horse that has been under stress from disease or sickness or injury does lay down from sheer exhaustion or body failure, they will remain “sternal” or on their chest with legs under neath them and withers up, for as long as they can manage. Horses that are healthy will sleep in the sternal position with the head curled around to the elbow, because this is an easier way to breathe. It is often in this position horses experience REM sleep.

The weather is a big factor in how much rest a horse can get. Cold, snowy, wet or windy conditions are not conducive to rest for most horses, and they are unlikely to lay down to sleep in such weather.  Just like people, horses rest best in a comfortable environment, and tend to follow the other horses in the herd. If another horse lays down, sometimes the rest of the horses may also lay down. Dr. Joseph Bertone, a profession of equine  medicine at Cal Poly Pomona, has studied sleep and sleep deprivation in horses, and has several articles published at www.thehorse.com that take a look at how much sleep a horse may need and what happens to a horse that can’t or won’t sleep. He says if you move a horse to a new situation – such as night turnout, or a new herd or pasture — sometimes it takes two to four weeks before they begin to cycle back to a comfortable sleep pattern. Two to four weeks! Wow!

Do horses experience REM (rapid eye movement, the deepest sleep) cycles? Researchers say yes but not quite the way humans do. Approximately 15 percent of a horse’s total sleep time is REM, and they may have the muscle twitches and rapid eye movements. REM sleep for a horse occurs while laying down because of the extreme relaxation of the muscles. So a horse has to be very comfortable in their environment to experience the deepest sleep.

Some horses do suffer from narcolepsy (sudden uncontrollable sleep periods) and cataplexy, excessive sleepiness. If a horse has constant, re-occurring sores on the front of the fetlocks or knees could be suffering from either of these disorders, which causes collapsing episodes where the muscles relax suddenly and the horse literally falls down. This is a sleep disorder and related to physical problems or an extreme problem in the environment that makes the horse’s sleep pattern disrupted. They recommend video surveillance of such horses to find out what in the environment is causing the behavior.

Standing sleep is also called “slow wave” sleep by researchers. A British study found that cribbers often don’t sleep on their feet or have as much slow wave sleep as much as other horses, 48 percent less.

So that’s a quick look at horses and sleep. Knowing that horses sleep some at night and some during the day actually makes me a bit relieved, and now I don’t feel so bad when I turn the barn lights on at 4:00 a.m. to load up to ship to a horse show! I know they’ll find sleepy time later in the day, and they don’t need that much anyhow! Good news!

— Holly