--- title: Sleep and hibernation — a lesson of Mova's school · trees and pragmatics description: «Sleep and hibernation», a lesson of the biology course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Every animal needs rest, but they rest in amazing ways: dolphins sleep with half their brain, giraffes nap standing up, bats sleep upside down, and --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/) / Sleep and hibernation # Sleep and hibernation Lesson 55 of the biology course of Mova's primary school: 18 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/biology/55-sleep-and-hibernation/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/0/) — Every animal needs rest, but they rest in amazing ways: dolphins sleep with half their brain, giraffes nap standing up, bats sleep upside down, and koalas sleep most of the day. - [1](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/1/) — Hibernation is something much bigger than a long nap: the body cools down, the heart slows from racing to crawling, and the animal lives on its stored fat through the hungry time of winter. - [2](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/2/) — Picture a hedgehog curled under a pile of leaves in November; its heart drops from about 190 beats a minute to around 20, and it stays almost switched off until spring, which is why bonfire piles must be checked before lighting. - [3](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/3/) — Some animals sleep through summer instead: the African lungfish digs into drying mud, wraps itself in slime and waits for the rain, and that is called aestivation. - [4](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/4/) — Cartoons show bears snoring all winter and waking up in spring with a big stretch, and goldfish forgetting everything in 3 seconds; real bears sleep more lightly than hedgehogs, and goldfish remember for months. - [5](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/5/) — Hedgehogs hibernate from about November to March, when there are few beetles, worms or slugs to eat; the heartbeat drops from about 190 to around 20 beats a minute, and they may wake and move nests a few times. - [6](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/6/) — Bears sleep through winter in dens living on their fat; their temperature drops only a little, mothers give birth in the den and make milk for the cubs from their stored fat, a bear wakes up thin and hungry in spring, and it can go months without eating, drinking or going to the toilet. - [7](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/7/) — The hazel dormouse can hibernate for six months or more, after fattening up on hazelnuts and berries in autumn. - [8](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/8/) — Dolphins sleep with half their brain at a time and one eye open, so they can still come up to breathe and watch for danger. - [9](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/9/) — Giraffes sleep very little, in short naps, mostly standing, because getting up takes a long time with lions around; koalas sleep about 18 to 22 hours a day, because their gum leaves give little energy. - [10](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/10/) — Bats sleep hanging upside down with their foot tendons locked, and in cold countries they hibernate in caves and attics; bats are not blind. - [11](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/11/) — Common frogs spend winter in mud or under logs, and some males rest at the bottom of ponds, taking in oxygen through their skin. - [12](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/12/) — The North American wood frog can freeze solid in winter, with its heart stopped, and thaw and hop away in spring. - [14](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/14/) — Children of 9 to 10 need about 9 to 12 hours of sleep a night; during sleep the body grows and repairs itself, and the brain sorts memories; bright light from a screen before bed tells the brain it is still daytime, so sleep comes harder. - [15](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/15/) — Fish have no eyelids, but many rest by slowing down and floating still; some parrotfish sleep in a bubble of slime. - [16](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/16/) — Mediterranean tortoises hibernate, and owners guided by a vet keep them steady at about 5 degrees so they neither wake early nor freeze. - [17](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/17/) — Waking up from hibernation burns a lot of stored fat that has to last the winter, and there is no food to replace it, so hibernating hedgehogs, bats and tortoises must be left alone. - [18](https://md.mova.elamur.ai/free/en/corpora/school/biology/55-sleep-and-hibernation/18/) — African lungfish survive the dry season sealed in slime in dried mud, breathing air, sometimes for years; this summer sleep is aestivation. - ← previous: [Migration: the great journeys](https://md.mova.elamur.ai/free/en/corpora/school/biology/54-migration-the-great-journeys/) - next →: [How plants grow: seeds, light, water and air](https://md.mova.elamur.ai/free/en/corpora/school/biology/56-how-plants-grow/) - ↑ back to [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/)