Dear Matthew Alice:
How come horses can sleep standing up? Why don�t they fall over?
-- Kris, Central Elementary School
Well, Kris, horses' legs are not built like yours and mine. The arrangement of bones and ligaments in their legs creates a sort of interlocking support system that its body rests on. Think of a sleeping horse as a body, neck, and head resting in a hammock hooked up to four trees. An animal is most vulnerable to predators whe it's asleep. And since the horse and its relatives depend on speed to escape danger, the ability to sleep standing up gives them a head start should they have to leap out of bed and run for their lives.