https://www.wikihow.com/How-Do-Horses-Sleep
Things You Should Know
Horses sleep standing up about 85% of the time, and sleep laying down the other 15%.
Horses have a group of muscles called a stay apparatus that keeps them upright while they nap.
The best place for a horse to doze off is in a safe, stress-free environment, like a secure stable or open pasture
Yes, horses spend 85% of their sleep cycle standing up.
This seems impossible, right? Well, maybe for humans, but not for horses! Horses have a special grouping of tendons and ligaments called a stay apparatus. This unique autonomic function helps them stay standing while they sleep. It’s also an amazing defense mechanism because if danger comes too close to a horse at night, they can wake up and immediately run away.
Horses spend the other 15% of their sleep cycle lying down.
Despite popular belief, horses can sleep on their stomach or sides. This 15% is spent in the REM stage of the sleep cycle. At this stage, the horse has to lay down because their muscles fully relax and their autonomic nervous system slows down.
Just like you, the REM stage of sleep helps a horse recharge for the next day. But where humans need about 90 minutes of sleep a night, horses only need around 30.
REM is short for rapid eye movement and is the stage of sleep when the brain is the most awake but the body is paralyzed.
Not mentioned in the article.
If a horse does sleep a long time on the ground they can develop colic, which is a digestive disorder similar to constipation.
This is a huge concern for horse owners. It can kill the horse if not taken care of.
