Next to another horse
There are no cold blooded horses...
Female horses sleep in the exact same places as male horses, neither sex has any one preferance when it comes to where they sleep.
Sea horses sleep by staying where they are
some examples of a horses functional adaptation, is that that they can sleep standing up. Their coat grows long in cold conditions.
Arabian horses sleep like most other breeds of horses. Horses can doze on their feet and take little 'cat naps' throughout the day. They will spend a couple of hours on the ground sleeping in a 24 hour period. Most breeds of horses follow this same sleep/wake pattern.
no
they sleep laying down
Yes, horses do lay down to sleep, but it is less common for them to sleep in this position compared to standing up. Horses have a unique ability to sleep both standing up and laying down, and will choose their preferred position based on their level of comfort and sense of security in their environment.
The Ground
horses
Probably when they get tired, like all other horses.
No, they don't.