When riding what safety distance must be between each horse?

Horses are large animals that need plenty of space. They can also be temperamental. When riding, a gap about the length of one horse should be kept between horses. (When riding abreast, the width of one horse should be kept between the riders). Horse's stalls should not be shared - each horse should have its own stall. The stalls should also be large enough that when standing in the middle of the stall, neither of a horse's neighbours can reach it. The horse should have room to turn around and lie down comfortably in the stall. The statement that horses all sleep standing up is a myth - horses can sleep standing up, but many prefer to lie down, and this takes the strain off their joints. Horses need at least an acre of pasture each.