Do Horses Lie Down? How the Method Changes It

Yes, horses lie down. Adult horses need recumbency to finish REM sleep, yet a glance from the aisle, a night of polysomnography, a wearable sensor, and a pulse count each return a different figure for how long that recumbency lasts and whether the animal is asleep or trapped against a wall.

Odourant in a buried propane line fades. A horse on its side can look like rest from the doorway and still be pinned. The method of looking is what changes the answer.

Why does a glance from the aisle disagree with an EEG?

A new owner who watches for ten seconds sees a large animal down and treats that as sick or not. Horses are polyphasic. They split rest across the day and night, doze on their feet, and drop into recumbency for the sleep stage that requires muscle atonia.

Linda Greening, equine sleep researcher at Hartpury University, and Sebastian McBride of Aberystwyth University, writing in Frontiers in Veterinary Science in 2022, pooled the published equine sleep studies and reported a mean total sleep time of 230.72 minutes. NREM occupied 178.74 minutes and REM 40.27 minutes. Most of that pool was standing. Recumbency is the smaller, necessary slice.

Change the instrument and the slice moves. Christine Wöhr and colleagues at Ludwig Maximilian University of Munich, using overnight polysomnography in seven stabled horses, recorded about 2.5 hours recumbent each night, with REM at 30 minutes (15 percent of total sleep time) and slow-wave sleep at 65 percent. Zsofia Kelemen, Florien Jenner, and Ulrike Auer at the University of Veterinary Medicine Vienna, using Trackener wearable sensors on 83 sanctuary horses for at least 60 continuous hours, reported a mean recumbency of 67.4 minutes per day, range 0 to 319. Eric Lim Teik Chung and colleagues, watching 15 adult Thoroughbreds in Malaysian stables for 24 hours, logged 57.00 ± 25.00 minutes sternal and 8.00 ± 6.00 minutes lateral.

Night EEG, multi-day accelerometry, and 24-hour video answer “do horses lie down” with three different clocks.

How long do horses lie down each day?

Joan-Bryce Burla and colleagues at ETH Zurich, in a 2017 Frontiers in Veterinary Science group-housing trial, treated 30 minutes of recumbency per 24 hours as the minimum needed for a minimum of REM, drawing on Dallaire, Kalus, and Williams. Feral and semi-wild horses in the studies they cite spent 30 minutes up to 2.7 hours recumbent per day. Kelemen’s sanctuary cohort sat at 67.4 ± 61.9 minutes. Horses with clinical REM-deficit signs in that same paper lay down for 7.99 ± 11.4 minutes; the others for 73.8 ± 61.8 minutes. Thirteen of 83 horses recorded no recumbency at all during tracking blocks longer than 72 hours.

Bedding moves the same clock. Greening, Downing, Amiouny, Lekang, and McBride, in Applied Animal Behaviour Science in 2021, cut bedding from a 15-centimetre control to a 5-centimetre treatment and watched lateral REM fall from 0.46 ± 0.13 hours to 0.34 ± 0.12 hours, and sternal NREM from 0.80 ± 0.12 hours to 0.64 ± 0.10 hours, while standing NREM rose. Pedersen and colleagues, as Greening later summarised, reported average lateral recumbency of 44.0 minutes on straw against 21.6 minutes on shavings or straw pellets.

Kelemen’s introduction states that adult horses sleep only 2.5 to 5 hours a day, about 80 percent of it standing, and still need the 30-minute recumbency floor to bank 3.5 to 4.5 minutes of REM and avoid collapse. A horse lying down too much is a separate problem. Catherine Torcivia of the University of Pennsylvania School of Veterinary Medicine and Sue McDonnell, founding head of the Havemeyer Equine Behavior Lab there, list atypical recumbency in their 2021 Equine Discomfort Ethogram as prolonged or frequently interrupted lying, sometimes lateral without sleep, often with groaning or difficulty rising.

How long is each time a horse stays down?

Torcivia and McDonnell, in the same 2021 ethogram, wrote: “For healthy horses, typical individual recumbency durations range from 15 to 40 min.” That is a stall observation, not an EEG epoch.

Kelemen’s sensors split the day. Between midnight and 4:00 a.m., lying bouts lasted 2 to 57 minutes (16 ± 15). Between 4:00 a.m. and 8:00 p.m., they lasted 7 to 12 minutes (10 ± 7). Between 8:00 p.m. and midnight, 7 to 16 minutes (10 ± 12). Greening and McBride’s pooled sleep-cycle length was 40.74 minutes; mean REM sequences ran 3.72 minutes and NREM sequences 6.02 minutes. Those last two numbers are sleep-stage lengths inside recumbency, not the whole time the body is on the ground.

A horse still down at 90 minutes, groaning or looking at its flank, has left that window. A horse down for 20 minutes after midnight, still, with a dropped lower lip and an ear twitch, is inside it. Healthy horses lie on their side for part of the bout: lateral recumbency is the posture most often paired with full REM atonia. Sternal recumbency, muzzle on the floor or a forelimb, can also carry REM if the head is supported. Standing rest carries NREM. Counting only “flat on the side” undercounts sleep; counting every buckle of the knees overcounts it.

What do resting heart rate and breathing say about a horse that is down?

The printed standards disagree, which is the point of taking the horse’s own baseline.

The Merck Veterinary Manual’s resting-heart-rate table, reviewed in September 2022 and updated in September 2024 by Susan E. Fielder, DVM, DACVP, of Oklahoma State University, lists the horse at 28–40 beats per minute. The same manual’s resting-respiratory-rate table lists 10–14 breaths per minute. Both tables are adapted from Dukes’ Physiology of Domestic Animals, 12th edition.

Canada’s National Farm Animal Care Council, in the 2013 Code of Practice for the Care and Handling of Equines, Appendix C, gives adult horses 28–44 beats per minute and 10–14 breaths per minute. The American Association of Equine Practitioners Horse Owner Education Committee, in a May 2025 owner-education post, listed 28–40 and 12–16. The American Quarter Horse Association, citing Dr. Chad Zubrod of Oakridge Equine Hospital in Edmond, Oklahoma, and AAEP as an alliance partner, published 30 to 42 beats and 12 to 20 breaths, and flagged a resting heart rate above 64 as a pain warning. Rutgers Equine Science Center fact sheet FS1262 gives 28–48 beats and about 8–14 breaths.

A barn card that says “28 to 40” calls 42 high; a card that says “28 to 44” does not. A sleeping horse should sit in the resting band already measured on that animal, standing and calm. World Horse Welfare, in advice last updated 22 June 2026 and externally reviewed by Sarah Coombs, BSc, BVetMed, MRCVS, notes that some cast horses remain surprisingly calm while down, while others kick, sweat, and show an increased respiratory rate and heart rate. A rate that stays high after the horse is standing, and the handler is still, is the reading that matters.

How is a sleeping horse different from a cast horse?

A cast horse has lain down or rolled too close to a wall, partition, or fence and cannot get its legs back underneath itself to stand. World Horse Welfare treats both collapse and cast as emergencies. From the aisle, a sleeping horse can share the same silhouette: large body, legs out, head on the shavings. Sleep, cast, and collapse share that first glance and then diverge.

| Sign | Sleeping horse | Cast horse | Collapsed horse | | --- | --- | --- | --- | | Clearance | Room on the wall side for the legs to swing out | Back or side against a wall, fence, or bank; legs often toward the centre of the stall | Down anywhere; the obstacle is the body, not the wall | | Motion | Still, or small REM twitches of ears, lips, or legs; can shift from lateral to sternal | Unsuccessful scrambling, kicking the wall, or a calm that breaks when someone enters | Floppy, exhausted, or uncoordinated; may be down from colic, fracture, heat, or sleep debt | | Typical bout | Minutes: Torcivia and McDonnell’s 15–40, Kelemen’s overnight 2–57 | Entrapment from the moment the legs cannot swing | Emergency from the moment found | | Heart and breathing | Inside that horse’s resting band (Merck 28–40 bpm and 10–14 breaths) | Often raised, with sweating, though World Horse Welfare records calm horses too | Often abnormal; the vet on the phone should hear the numbers | | Rise | Unassisted, after a roll to the chest and a head-and-forehand heave | Needs a controlled roll away from the wall, then space to stand | Needs a veterinarian; rolling a fractured or colicking horse can worsen the injury |

Torcivia and McDonnell also flag difficulty rising: a horse clear of the wall that still cannot stand is a down horse.

Rebecca Gimenez, BS, PhD, of Technical Large Animal Emergency Rescue, Inc., writing with S. Smith in the 2017 AAEP Proceedings, put the physiology in one sentence: “The sheer weight of the animal contributes over time to compartment/crush syndromes, myopathies, neuropathies and requires that the animal be attended quickly—within 4 hours of being down for the best opportunity at recovery.” That 4-hour figure is a rescue-medicine clock for a horse that cannot rise.

A veterinary nursing chapter on recumbent-horse care, published on Veterian Key, states that muscle damage can develop in as few as 2 hours, and that horses unable to rise or roll themselves should be repositioned every 2 to 6 hours. World Horse Welfare’s public advice offers no waiting period: call the veterinarian as soon as the animal is found. Immediate (World Horse Welfare), 2 hours to muscle damage (nursing chapter), and 4 hours for best recovery (Gimenez, AAEP 2017) are three clocks. The shortest one governs a stall at 2 a.m.

How many times do horses roll, and when is rolling an emergency?

Rolling is ordinary coat care. It is also a colic sign. The difference is the count, the setting, and whether the horse gets up.

M. N. Hansen, J. Estvan, and Jan Ladewig of the University of Copenhagen, in Applied Animal Behaviour Science in 2007, watched 43 horses on pasture from 03:00 to 10:00 over four mornings. Rising was seen in 41 horses. Twenty-five of those 41 (60.9 percent) rolled at least once before standing. Of 135 rising episodes, 41 (30.4 percent) followed a roll. Outdoors, some horses rolled 45 to 180 degrees, some repeatedly; horses in a box, in the authors’ earlier indoor work, had rolled 90 degrees and back.

A single roll after a nap, then a shake and a return to hay, sits inside that 30.4 percent. Repeated rolling, getting up and going straight back down, looking at the flank, pawing, and refusing feed is the colic pattern. Torcivia and McDonnell list rolling among discomfort behaviours. A horse that rolls next to a stall wall is the animal that becomes the cast horse in the table. The roll is ordinary. The wall is not.

How long can a horse stay down if it cannot rise?

A healthy recumbent episode ends when the horse rolls to its chest, unfolds the forelegs, and stands. A horse that cannot finish that sequence is on Gimenez’s clock. Gimenez gives 4 hours as the best-recovery window for crush and compartment effects. The nursing chapter gives 2 hours to the start of muscle damage. World Horse Welfare, with Coombs as external reviewer, treats the find as an emergency with no published grace period. No agency in that set recommends leaving a horse that cannot rise to “sleep it off.”

Sleep deprivation produces a different down horse: one that was never recumbent enough. Kelemen’s eight REM-deficit horses averaged 7.99 minutes of lying per day. Several showed the carpal and fetlock scrapes that come from buckling into REM while still standing. Burla’s 2017 paper describes horses reluctant to lie down that “transition into REM sleep while standing, partially collapse, and then wake up suddenly,” a behaviour “commonly but incorrectly diagnosed as narcolepsy.” Recumbent-sleep debt is the usual finding. True narcolepsy is rare.

Kelemen recorded recumbency across 24 hours, with a peak between midnight and 4:00 a.m., and with individuals that slept only at night, only by day, or in scattered bouts. Daytime recumbency after work, in heat, or in a quiet paddock can be sleep. Sweating, a heart rate stuck above the Merck 28–40 band, and no rise when asked, is the other list.

How to tell sleep from a cast horse in the stall

From the doorway, without stepping into the limb arc:

1. Stay outside the stall and look at wall clearance before touching the horse.
2. Time the recumbency; a still bout of 15 to 40 minutes with small twitches is the healthy window.
3. Watch whether the legs can swing out. Legs toward the centre and the back against a wall is cast, not sleep.
4. If the horse can be approached safely, count heartbeats and breaths for 15 seconds and multiply by four; compare them with that horse’s rest and with Merck’s 28–40 and 10–14.
5. Call a veterinarian if the horse cannot rise, is thrashing, has been down beyond a normal bout, or shows colic rolling.

FAQ

Do horses lie down to sleep?

Yes. Horses doze standing, but REM sleep needs recumbency. Greening and McBride’s 2022 review put mean REM at 40.27 minutes inside 230.72 minutes of total sleep. Kelemen’s Vienna sensor study used 30 minutes of lying per day as the floor against REM deficit. The horse that never lies down is the one at risk.

How long do horses lie down each day?

The method sets the number. Kelemen’s wearables averaged 67.4 minutes (range 0–319). Wöhr’s overnight EEG recorded about 2.5 hours recumbent. Burla treated 30 minutes as a REM minimum. Feral reports run from 30 minutes to 2.7 hours. Name the instrument before treating any figure as the horse in the stall.

Why is my horse lying down during the day?

Daytime recumbency can be sleep. Kelemen found most lying between midnight and 4:00 a.m., but some horses lay only by day. Heat, a heavy ride, or a quiet paddock can shift the clock. Sweating, a high resting heart rate, repeated rolling, or a failure to stand when asked means the bout has left sleep for colic, cast, or collapse.

Is a horse lying on its side an emergency?

Healthy horses lie on their side for REM. Torcivia and McDonnell put typical bouts at 15 to 40 minutes. It is an emergency when the horse cannot rise, is cast against a wall, is thrashing, or has been down long enough to hit the 2-hour muscle-damage mark in recumbent-nursing texts or Gimenez’s 4-hour recovery window.

How can I tell if my horse is cast?

A cast horse has its back or side against a wall, partition, or fence and cannot swing the legs under the body. Sleeping horses keep clearance. World Horse Welfare describes both calm and frantic cast horses; either way the animal cannot stand. Stay out of the limb arc, call the veterinarian, and do not pull legs by hand.

Do horses sleep standing up or lying down?

Both. NREM and drowsiness happen standing, thanks to the stay apparatus. REM requires recumbency, sternal with the head supported or lateral on the side. Greening and McBride’s pooled data gave 178.74 minutes of NREM and 40.27 minutes of REM. Counting only standing rest, or only flat-out naps, misses half the sleep.