Is it true, as I read most places, that giraffes sleep less than any other mammal?
How is this possible? Have scientists been able to figure out how they are able to function properly on so little sleep? What is different about their brains than other mammals?
I mean, kitties sleep huge amounts of time. Humans sleep 1/3 of their life or so. How do giraffes do it?
I’ve read they sleep as little as a few brief, deep naps and as much as 2-3 hours per 24 hour period.
I have no idea - and I didn’t know giraffes were such freakish creatures aside from their necks - but I’m intrigued if there is any answer. 
It is kind of neat.
I’ve done basic Google searches and it seems to be a mystery. I’m curious if any further research has been done.
Dolphins and I think other cetaceans sleep on only one hemisphere of the brain at a time. It’s kinda hard to compare a process like that to the “complete unconsciousness” that other mammals undergo. If the fact is true, might have to qualify with land mammal or something more specific, or at least define what you mean by “sleep.”
OK. Land mammal.
Some other animals don’t sleep much. Horses and goats can be very light sleepers. The light sleepers are usual grazing animals in danger from predation. A giraffe can’t hide very easily, so if it fell into a deep sleep, it might wake up dead, so to speak. Giraffes are reported to lean their heads back over their bodies when they sleep. Their long neck is very specialized to provide sufficient bllod to their brain, so possibly they can only sleep in that uncomfortable and dangerous position.
I couldn’t find a cite for this, but I’ve heard that some animals which hibernate will stay awake for almost the entire season they are up and about. There are also a number of theories about human sleep that claim sleep is necessary for the brain to keep itself organized. I wonder how much organization a giraffes brain actually needs.
Not much.
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How Do Giraffes Sleep?**
Well, he does always seem to be online…
Nice.
(my bolding)
A big part of the disparity is diet: carnivores sleep way more than herbivores as a general rule of thumb. Part of that is that as prey animals, herbivores need to remain alert; part of that is the fact that digesting protein requires a lengthy and blood-intensive process. This is why you’ll see lions stuffing themselves on zebra meat and then lying around nearly motionless for a day after that, sleeping and digesting, while all around them the remaining zebras are grazing almost constantly, on the lookout for the next hunter.
I don’t know about giraffes - but horses have something call a Stay apparatus that allows them to sleep standing up. They basically hook strategically placed tendons over bony protruberances and remain standing without effort.
Horses can remain standing for literally years at a time - but they do sleep at regular intervals anyhow.
Here is a thread on the same topic(well, it started out with the opposite question, but has a lot of relevant info).
One thing that makes giraffes more vulnerable than other prey animals is that if you’re 18 feet tall it’s kind of hard to find a good hiding place for the night.
Maybe our own Giraffe will be along to answer. When he wakes up.
I have no idea what “blood intensive” means, but if protein is digestible at all (some types aren’t digestible by mammals) it requires far less time than digesting the grass and leaves that giraffes live on. This is why the guts of carnivores are less than a quarter the length of herbivore guts.
As far as being “prey animals”, far more carnivores are prey animals than are herbivores. While the largest herbivores in most ecosystems are almost totally safe from predation, the same is virtually never true for predators. Think about it. Adult elephants are never preyed upon, adult buffalo and giraffes are very, very rarely preyed upon. In contrast most adult cheetahs and lions end their lives being killed by other predators, and more juvenile lions are die at the hands by other predators than through any other means. So how do you figure that giraffes need to be more alert to predators than lions, when lions are preyed upon more with greater frequency than giraffes?
The simple fact is that predators sleep a lot because they can. They eat a very energy dense and readily digested diet, meaning they can consume all the required nutrients for several days in the space of just a few minutes. After that they can avoid using energy unnecessarily, conceal themselves from predators, avoid exposure to climate and avoid water loss by remaining inactive. So of course that’s just what they do.
If herbivores could manage to obtain all their required nutrition in just a few minutes a day, you can be damn sure they would sleep the rest of the day as well. But they can’t. Plant matter is hard to digest and dispersed across the landscape, so herbivores generally need to spend most of their time feeding.
But giraffes are demonstrably *not *more vulnerable than other prey animals. Giraffes are preyed upon at exactly the same rate as other animals their size. And that rate is negligible, certainly much, much less than the rate at which smaller animals are preyed upon.
Finding a hiding place simply isn’t an issue for an animal that can neither climb nor burrow. All the predators have exceptional hearing and olfaction, so they will find you, regardless of size. The best protection is simply to become so big that you can’t be hurt, and that is precisely what all the megafauna, including the giraffe, have done.
Which is why giraffes are much, much *less *vulnerable to predation than wildebeest or zebra, and only slightly more vulnerable than the slightly heftier hippo.
Maybe the danger to sleeping giraffes is physical damage to their bodies. It can’t be easy for them to lay their heads back over their bodies, but otherwise they might be in danger of a neck injury. And if there legs can’t lock as well as a horse’s, falling over could be very dangerous. Giraffes are very large, and heavy, I doubt they could survive a leg fracture any better than a horse. And a giraffe on the ground may be a likely target for predation.
I don’t know what happened to the post I put in earlier this evening, so I’ll repeat something here: The interesting part is that the highly specialized giraffe hasn’t given up sleep altogether, if sleeping is difficult or dangerous to do.
Interesting idea. The similarly-shaped camels sleep kneeling down, but the more extreme proportions of the giraffe presumably mean that it takes much longer to stand from a kneeling position and is at much greater risk while doing so. So you may be onto something.
If you can’t sleep standing and you can’t safely lie down to sleep, you have something of a dilemma.
Agreed.
One theory on sleep is that it keeps organisms out of danger. e.g. Humans have specialised for daytime activity, so we sleep at night to keep us from wandering about at a time when we can’t effectively do anything (sans lightbulbs).
The main problem with this theory is why we go into a deep sleep and not into an alert but resting state, which would be much safer.
But it occurs to me that the situation with giraffes presents a much more difficult problem to explain from this perspective, and may destroy the theory outright.
He doesn’t sleep, he waits.
Don’t say that. The makers of the BBC series “Planet Earth” managed to film a pack of lions that killed an elephant.