why do some animals sleep standing up?

u didnot see it sleeping. a horse rarely sleeps.

I really don't know. Do you? They do lay down too though.

Definately for the survival.

i think they feel comfortable in standing

I don't know why it be.| www.igho.web.id

I have know idea why they sleep standing up i guess they just like standing up..........

Let's of animals sleep standing up for protection when they're outside.Inside horses and cows will lay down because they feel safe.If you ever see them try to get up from laying down,you'll understand why.It's very hard and awkward for them to get up quickly becasue of their body mass.Thus they would be easy prey for preditors.

Because they are really tired? hahahahahahahaha Seriously, because in the wild, even when sleeping, they have to be ready to run if danger was imminent.

i think they feel comfortable in standing

yes hores sleep