Like lots of other herd animals, horses sleep standing up. Horses are prey animals and one of their best defences was their turn of speed and ability to out run the predator hunting them.
Therefore sleeping upright gives them a better start to fleeing a potential predator than lying down would - and those extra seconds could be the difference between life and death.
Do horses sleep standing up?
Yes. Horses are able to sleep standing up because of their 'stay apparatus'.
When the horse relaxes muscles, tendons and ligaments work together so that the horse can sleep standing up without worrying about falling over.
To help lessen the danger that comes from lying down one horse will always stand guard over the rest of the herd, ready to warn of impending danger - and urge the herd to its feet.
Other animals that sleep standing up include birds, bison, zebras and elephants sleep standing up. Cows can too, but mostly choose to lie down. Giraffes also sleep standing up, but only for short periods of time.
How long do horses sleep?
Horses usually require 4-5 hours of sleep each day, most of which can be achieved standing up.
Saddle up for a journey into the equestrian world
Ever wondered if horse riding is a sport? Or are you curious about the ins and outs of equine ownership? If so, check out our feature about how much it costs to own a horse.
And, if you're looking for present ideas, don't miss our handpicked selection of best gifts for horse lovers.