Worse than sloth

I've been having trouble sleeping lately, so I was particularly annoyed when I came across this table of, basically, animals that get more sleep than you do.

Never mind the sloth, which is in eleventh place on the list and sleeps a mere 14.4 hours per day on average, and as we've seen before is not nearly as slothful as it would like you to think. Seethe, instead, at the following numbers:

Brown Bat 19.9 hr
Giant Armadillo 18.1 hr
Opossum 18 hr
Python 18 hr
Owl Monkey 17.0 hr
Tiger 15.8 hr
Tree shrew 15.8 hr

As you'll see if you click on the link, that is, for example, 75% of the day for the python. And there's lots more. Even a gerbil sleeps thirteen hours a day. Thirteen hours! What's so hard about being a gerbil that makes them tired enough to need thirteen hours of sleep? What kinds of ideas do gerbils have to come up with? What kind of deadlines do stupid little rodents have to meet? Seriously. Gerbils.