How much do animals sleep?
 

I used to own a bird. And I can see it asleep no matter how late I stay up or how early I get up, though I never see it being sleep deprived.

Humans are animals. How much do we sleep? (Not answering your question). The amount of sleep required differs across species. Search for it on google. One example can be found here:

http://www.sleephomepages.org/sleepsyllabus/fr-b.html

Lions sleep an average of 16-20 hours a day.

Birds are an interesting case, apparently many species seem to be capable of putting one hemisphere of their brain to "sleep" while the other hemisphere remains "awake".

Sleep is a pretty complicated biological phenomenon and I think studying animals will give good insight into human sleep.

Anyway, I wanna be a lion.:)

Most cats sleep for much of the day, as they are predators and need to conserve their energy for the chase, even if they are lazy housecats and don't do anything else but eat from a bowl and tear up the furniture. I'll take "little brown bat" for 20 hours a day, Alex.

Yeah, cats are freaking amazing when it comes to sleep, but then again, most biologists also put cats as one of the most efficient hunters, so they don't have to stay awake very long hunting food.

my housecat sleeps probably between 10-16 hrs a day..most of those hours during the day when everyone is gone, then he is a charging, 20 lb monster at night......

hmm...Predators sleep alot. Preys sleep little....hmm

Universally true? at least in the wild?

ahh sleeping.
the first thing you have to overcome is the idea that animals only sleep in one block, like humans. while this is the case of animals higher up in the food chain who can afford to, most animals don't. in fact, given the conditions, humans will actually prefer to take their sleep in two 4-5 hour blocks.

what most animals do is sleep in short burst, says 10 minutes long, throughout the day. birds are quite adept at this, hiding in a bush, taking a quick nap, then getting back to incesant tweeting. another action employed, as macheath said, is to sleep one hemisphere at a time.
ducks have been shown to do this, and be responsive as to which side of the brain they sleep at one time. aquatic mammals also do this, whales will sleep one hemisphere, so that the other is awake to send it up for air everyso often, and keep searching for food.

I know that certain sharks can't stop swimming or else water stops flowing through their gills and they suffocate. When to they sleep?

if you ever see a shark documentary on, watch it, they've got some good pics of shark sleeping most of the time.
basically, sharks that have to keep moving go into huge swimming circles (think circling vultures underwater) and swim around in circles while they sleep.
it's a simple exercise, and they can easily pull it off while taking a nap, so, thats how they sleep.
as for when, no clue, depends on the shark:p

Tyler Durden-ish. Very eery. Imagine if you could train yourself to do that, that's a third of your life you get to use.

just need to train the mrs. to be able to do the same thing and your in business:icare: