“Without exception, every animal species studied to date sleeps or engages in something remarkably like it. This includes insects, such as flies, bees, cockroaches, and scorpions; fish, from small perch to the larger sharks; amphibians, such as frogs; and reptiles, like turtles,  Komodo dragons, and chameleons. All have a bona fide sleep cycle. Ascend the evolutionary ladder further and we find all types of birds and mammals sleep: from shrews to parrots, kangaroos, polar bears, bats,  and, of course, we humans. Sleep is universal.”