Every night before turning in I do barn check. By the time I get there my donkeys have almost always “put themselves to bed” by coming into their shared stall from the paddock. Invariably Shiloh stands at the stall door facing out at the world. His buddy Shamus is stretched out, fast asleep. Shiloh is the barn watchdog. Whenever there is more than one equine in a herd, there will often be one self-appointed guardian that watches over the others. In the natural horse world, this is usually one of the mares of the herd. When this job gets taken so seriously that the watcher never gets a chance at sleep, things start to come apart for them.
Research has shown how important sleep is for both us and for horses. Horses have three levels of sleep. They need about 2 hours of a very relaxed drowsiness and 3 hours of “slow wave sleep.” For these first two levels the animal is still on his feet and easily aroused. The last phase is called REM (rapid eye movement) sleep. In REM sleep the horse is either flat out or on its sternum with head turned to the side. They don’t wake up right away when stimulated. Horses need 30 to 60 minutes of this deepest sleep. If you watch carefully you can see the eye movement, even through the closed lids. In this deep stage the brain waves change, and the restoring, healing work of the body takes place. (Humans need 2 to 3 hours.) If horses get less than their requirement for a few days in a row, interesting things start to happen. Basically, the sleep deprived horse tends to fall asleep on his feet. These horses will sway forward and back and actually buckle at the knees and go down, often catching themselves after the front of the fetlocks or the knees hit the ground. There are some videos of this which you can access by googling “sleep deprivation horses videos.” Veterinarians often recognize horses that are sleep deprived by noticing scarring on the front of the fore leg fetlocks. Some horses need that sleep so badly that they will sway and go down in cross ties when feeling secure while being groomed. We have all experienced what this must feel like as we try to stay awake when driving after a night of little or no sleep.
I am embarrassed to say that years ago I diagnosed horses that fell down from a standing position as being narcoleptic. Narcolepsy is a specific neurologic problem in people in which one goes from wide awake into a coma like state at inappropriate times. I have a friend who used to fall asleep right into a plate of his food until he was put on the right medication. It turns out that narcolepsy is extremely rare in horses. In looking back, each horse that I and other veterinarians thought had narcolepsy, were most likely sleep deprived. Dr. Joe Bertone from Western University in California is credited with being the first to recognize the syndrome and how to deal with it.
Why would horses not relax, lie down, and go into deep sleep? After all, as far as we know they don’t carry the load of worries or party late like us. There are a couple of reasons that have been identified. One is the social situation. The “guardian horse” feels he must stay awake to protect the herd. Perhaps the animal is in a noisy or scary stabling situation. This is the case at week long horse shows where the lights are always on and the activity level is high 24 hours a day. There are also some animals that don’t want to lie down because they have arthritic joints, making getting up and down painful. These horses may get their first good sleep in weeks when put on anti-inflammatory medication.
There are some issues that should alert you to the possibility of your horse missing out on deep sleep. A very natural and daily activity for horses is going down and having a good roll. If you have never seen your horse roll, it may be because he or she has some soreness that makes this activity painful. If a horse doesn’t go down to roll, he or she probably won’t go down to sleep. Evaluate for soundness any horse that you never see rolling. Obviously sleep deprived horses will not perform to their potential.
Whenever the social situation changes, as it does at horse shows, be aware that your horse may become sleep deprived during that time away. Sometimes it helps to change who the horse is paddocked or stabled next to. Putting a pony in with a sleep deprived horse may allow him to relax and catch up on his healing sleep. I think that some horses won’t lie down because there just isn’t enough room in their stall. I generally recommend a 12 by 12 foot stall for a 1000 pound horse.
If you suspect a horse with this condition in your barn, talk to your veterinarian. For sure he or she has seen this before and will have suggestions based on your situation.
–David A. Jefferson, DVM