Horses do not sit.
It's actually impossible for horses to sit down.
However once laying down the horses can sit back up and get up but they do not sit down on their butts as it's not possible.
Horses are unable to bend their rear legs and sit on the ground; it's anatomically impossible.
The horses weight would cause them to crash into the ground and possibly injure themselves.
Horses can rest standing up or lying down.
The most interesting part of horses resting standing up is how they do it. In horses there is a special arrangement of muscles and the parts that connect muscles and bones together (ligaments and tendons).
This is called the stay apparatus.
Horses usually sleep while standing due to the stay apparatus in their legs, but there is no denying that they sit down to get 3-4 hours of REM sleep.
Besides sitting down for rest, they also sit for various reasons, for instance, when, They are sick.
Instead of falling into a deep sleep every night, horses typically spend their nights alternating between rest and activity.
They might take a short snooze standing up, graze for a while, and then stretch out on their side to get a few minutes of deep sleep.
Horses are mammals and they will inevitably get cold just like the rest of us in harsh winter weather.
But you don't need to keep your horse inside all winter; horses are able to withstand colder temperatures thanks to their hardy natures.
Horses have excellent night vision. Horse eyes are large, they have a large pupil, and this allows ample amount of light to enter even in dark situations.
On a night lit by a partial moon or stars, horses can see just as well as people can in full daylight.
Horses let humans ride them because of a relationship of trust developed through hard work, time, and training.
Humans sitting on the back of a horse and guiding it isn't natural.
In the wild, horses run when humans attempt to approach them.