Why do some four-legged animals sleep while standing?
The animals which sleep standing up are all grazers, and the reason they sleep standing up has a lot to do with simple anatomy. Grazing quadrupeds do not have a full diaphragm like we do, that separates their guts entirely from their lungs — and they have an awful lot of gut, because you need that length of gut to break down the insoluble cellulose in what they eat. So this gigantic bag of guts just kind of hangs there inside the skin, protected by the ribs. Also, in many animals the lungs are attached directly to the ribs and breathing *must* involve motion of the ribs. Now, when the animal lies down, this compresses everything: the ribs get squished in along where they lie, and the guts get squished up inside them, and the guts tend to squish up around the other organs — including the lungs, which can’t move as much as normal anyway and which also put further pressure on the heart. The smaller the animal is, the less this is a problem; the less overall weight and compression there
The reason that I have found that some animals “sleep standing” is usually because of their weight. Most animals that “sleep while standing” are larger animals such as cows. People speak of going “cow tipping” when it reality it is impossible. Because the cows do not acutally “sleep standing”. You will hardly ever see a larger animal like this asleep lying down because they sleep in only 5-10 minute incriments. If they sleep lying down for too long then their weight will cause them to break a rib. I saw this on the discovery channel and hope my answer is very usfull to you!
