Sleep Deprivation in Horses

Paradoxical sleep is when your horse lies down on the ground and allows the cycle of sleep in all its stages to occur. Because of their evolutionary history where your horse would have been a migratory species, equine sleep patterns were influenced by environment and physical factors. With packs of wolves or other predators roaming about, your horse had to be careful when they slept to avoid being dinner for the predator.

Horses can usually go for several days without paradoxical (deep) sleep but when your horse goes past the several days, sleep deprivation sets in.

• Your horse may not lay down at all which is the tell-tale sign of sleep deprivation as horses need to lie down to experience restful sleep
• Your horse may seem very drowsy and sleepy during the day 
• Performance may falter
• Your horse may fall asleep while standing and collapse as he goes into REM sleep 
• Bruises and abrasions may occur on your horse’s knees when he falls down

Types  

• Dominance displacement – An aggressive gelding that is trying to take control of a herd with no leading mare – this causes anxiety and insecurities 
• Monotony induced sleepiness – This near collapse state comes from monotony and your horse is very comfortable and nearly falls asleep on his feet
• Pain associated sluggishness – If your horse associates pain with lying down and getting up again, then he will avoid it
• Environment insecurity causing excessive drowsiness – Your horse is insecure and on guard so will not lay down to rest

• Being alone – Your horse is a herd animal and may feel vulnerable on his own 
• Being in a new environment, for example moving often between shows 
• Noisy location at night – The noises are foreign to your horse
• Inadequate bedding making it uncomfortable in a stall 
• New outdoor environment that they are not used to 
• Too small a stall making lying down impossible 
• Pain will often stop a horse from lying down

If your horse is showing signs of sleep deprivation, you may need an equine specialist to diagnose this condition. The diagnosis relies on physical examination, observation of your horse’s behavior, and blood work in order to rule out a physical cause that may be inhibiting your horse from lying down comfortably. Additionally, if the veterinarian feels it is required, he may suggest an MRI or neurological work-up. 

You can do much to help your horse to feel safe and comfortable to allow him to relax and lie down to get the sleep he needs and evaluate whether the changes have helped him. Some questions you can ask yourself as an owner are as follows. Has your horse’s environment changed? Perhaps a new horse has been added to the paddock who is very aggressive. Have you seen your horse lie down and roll lately? if the answer is yes, then it is not a physical problem stopping him from lying down. And finally, is your horse’s environment calm and peaceful, or has he been moved to a pasture near a motorway or housing development? These things can unsettle your horse, preventing them from allowing themselves to rest fully; they are constantly on the alert. Change these things and your horse may be able to relax and get a good sleep.

Many horses need a strong dominant mare in the herd in order to feel comfortable enough to relax and sleep. Mares are the sentinels who watch over the other horses allowing others to rest. If your horse is all alone he may feel vulnerable and spend most of his time on guard. Observation is the best key to understanding your horse; if he is alone he may need another horse to feel comfortable. If it is obvious that your horse can lay down and get up again after rolling, then something other than pain or physical condition is stopping him from lying down to get his deep sleep. Watching to see how your horse reacts to a new environment or a noisy neighbourhood will allow you to find the cause of his discomfort. Perhaps moving to a quiet pasture at night will overcome the noise situation. Although horses can go longer than their human friends without decent sleep, it will catch up with them eventually. 

Sleep deprivation can be caused by a medical issue and once the problem has been diagnosed and treated accordingly your horse should again be able to lie down comfortably and obtain the sleep he needs. If your veterinarian does not find a physical cause, then together, you and the veterinary specialist can make observations about the environment in which your horse spends his days and nights and put forth the necessary changes.

Usually once you have established what is upsetting your horse and you take measures to correct it, your horse will finally relax and give in to get some much-needed sleep. Recovery is usually quite quick, but you do need to work out what the cause is. Effective management strategies such as moving your horse away from a potentially aggressive horse, or moving them away from a noisy environment or barking dogs will help. If your horse is stabled, ensuring that they have room to lie down on good comfortable bedding will help. Sleep deprivation is usually caused by environmental insecurities so if you can find out what they are and fix that, it will help your friend. If all else fails and your horse is having real trouble relaxing, your veterinarian can return and give some assistance to relieve your horse from this condition.