When I was young I was always told about the notion of cow tipping. Today the idea does sound cruel but these were different times and the idea of a cow asleep while standing, being tipped over in the middle of the night, did sound pretty funny to our childish minds. I lived near many farms and would often try and catch a cow asleep on his feet, but I never did. Whenever I approached a cow in my best stealth mode, they were always too smart for me. Now in the age of the internet, I have put more research into cow tipping and found that most people have failed. It now appears to be a rural myth!
The main reason that cow tipping is impossible is that cows don’t sleep standing up. While they can doze off while standing, to reach a true REM state they need to lie down. Of course then, if you try and sneak up on a cow it will realize and be pretty annoyed. The same is true for most large land herbivores.
Some animals do have something called a stay apparatus. This means that they can stand for long periods of time without tiring. Their limbs contain muscles that allow them to stand with ease. This is why they are able to doze off and we (usually) are not. Yet to enter a deeper state of sleep they will curl up on the ground.
Some herd animals such as bison will not all sleep at once. A number will remain to stand and keep watch over the heard to warn of any predators (or tippers) approaching. Some animals also just don’t need a lot of sleep. Giraffes, for example, will often only sleep for 5-minute spells at a time. Overall then, large animals are like us, they lie down for a nice sleep. They are just a little better at having a quick snooze while standing on the job.