For us humans sleeping while standing up is not really possible. Yes, you might doze off in a bit of a quite upright position if you’re really sleep deprived, but the thing is, we humans don’t posses legs that can really lock in position, align themselves so to sustain us during sleep. Why would you need these kind of legs? Because during sleep, muscle activity is slightly decreased and you would just fall down if not naturally equipped with this kind of skeleton. But, there are some animals who do sleep standing up. Take horses for example. Their knees just lock into place and they can doze off to dream land while on their feet. Still, they sometimes need to lie down for an hour or two, but not as much as we humans need. So, why sleep standing up, after all? It seems quite uncomfortable to us humans. Let’s see!
Big animals sleep standing up
In the wild, big animals like zebras, elephants mostly sleep standing up because they’re quite large and getting up requires a lot of effort and time and in the case of being attacked by, say, a pack of lions, time is essential. This does not mean that zebras and elephants do not lie down sometimes. They do, but mostly when they feel safe. Cows can also sleep standing up, although they usually prefer lying down.
Flamingos’ natural habitat is usually caustic salt flats. This means they can’t lie down, so they just sleep standing up. Also, birds which sleep in the trees, at night, have a quite complex system which enables their leg tendons to use their body weight to shut the claw around the branch and thus they can sleep safely in the tree. This is also some kind of sleeping standing up.