Horses spend most of their time sleeping standing up, but they don’t actually reach full REM sleep when they’re standing. During REM sleep, the brain consolidates and processes new information for long-term memories. Horses require 30 to 60 minutes of REM sleep daily and they can enjoy a light sleep while standing up. The benefits of sleeping on their feet include the ability to quickly become alert and galloping away from predators if needed. This is a survival mechanism for horses, due to their evolution as a prey species.
It takes a fair amount of effort for horses to get up after lying down and the few extra seconds this takes could be the difference between survival and being caught by a predator. Also as horses are large animals, if they were to lay down for extended periods of time, their blood flow would become restricted, resulting in further pressure on their internal organs, which is another good reason to stand up while they are sleeping most of the time.
A horse will usually only lie down to sleep for two or three hours a day in intervals. They often also have another horse with them who will act as lookout while they sleep.
Evolutionary and Physiological Adaptations
In order to understand why horses sleep standing up we have to look back to where and how they evolved. Being prey animals that originally lived on wide open plains they needed to be able to run at a moment’s notice and it’s far quicker to run from a standing position than it is if you’re lying down. Horses can sleep standing up, but not deeply. They have a special system of tendons and ligaments which enables them to lock the major joints in their legs so that they don’t fall over.
When horses need deep sleep, they lie down, usually for short intervals that amount to about two to three hours a day. Even then they often have another horse standing nearby serving as a lookout.
Do Horses Ever Lie Down to Sleep?
Yes, a horse usually only lies down to sleep for two or three hours a day in intervals and often with another horse standing guard.