Anyone who has ever spent any time around horses knows that they are can sleep standing up. This is thanks to what is known as the stay apparatus. The muscles on opposing sides of the joints in a horse’s limbs are able to contract and relax as needed to keep the limbs straight. As prey animals horses have evolved this way because it allows them the benefit of sleep while allowing them to flee a predator if needed. As prey animals the amount of sleep they require is also quite short. On average horses sleep two and a half hours in a 24 hour period. What we sometimes forget is that horses do need to lie down in order to cycle through all the stages of sleep and reach REM sleep. Horses require approximately 30-40 minutes of REM sleep in a 24 hour period. This can be done flat out on their side or on their sternum with their nose resting on the ground. Since they evolved as migratory pray animals they are able to skip this stage of sleep for a few days, but over time sleep deprivation will kick in. Sleep research in horses is a relatively new field of study and certainly not as extensive as in people, but it appears it is a common problem.
Horses who are sleep deprived due to not getting enough REM sleep can display a few different symptoms. They can become hard keepers, their behaviour will start to change (more likely to spook or be distracted), they can buckle at the knees, usually catching themselves, but will sometimes even fall down. These falls can lead to wounds on their fetlocks and below the knees. I have also seen excessive muscle tension in horses who have suffered with sleep deprivation for extended periods of time, most likely caused by repeatedly catching themselves when falling. Massage can help with the resulting tension, but changes must also be made which will allow the horse to lie down. Sleep deprivation leads to increased cortisol levels which has negative effects on many of the body’s systems including metabolism, the immune system and hormone levels all of which adds up to decreased performance. Definitely an important factor to consider for your equine athlete!
If you suspect your horse is not laying down to sleep and are not able to manage their environment in a way that addresses this, it is important to speak with your vet. Most of the time horses don’t lie down due to environmental factors. For example, a horse kept on a property by themselves may not feel secure enough to lie down and a similar situation can occur if a horse has an aggressive buddy turned out with them. Lack of a comfortable place to lie down or a stall that is too small can also keep horses from lying down. Moving to a new barn, going to a horse show, any big change really can also affect horses’ sleep patterns at least in the short term. Finally, horses with pain issues will often not lie down because getting up is too difficult. This is often the case in older horses with arthritis issues. If you suspect this may be the reason your horse is not lying down, speak to your veterinarian who can help with choosing a pain management protocol that will help make the horse more comfortable.