As they grow, they take fewer naps and prefer resting in an upright position over lying down. Adult horses mostly rest while standing up but still have to lie down to obtain the REM sleep necessary to them.

Do horses lie down to sleep at night?

Horses have an amazing ability to be able to sleep standing up. But they do also sleep lying down. If you're a horse, you need to be able to do both.

What animals sleep standing up?

Horses, zebras and elephants are just 3 examples of animals that can sleep standing up, because it allows them to quickly escape an attack by a predator (the process of standing up can be slow and clumsy).