Many ways to sleep

How do you sleep? Most people sleep on their backs or sides. 1. Do animals sleep the same way? Actually the ways they sleep are much more different—they can lie down, sit or stand while they sleep.

Swiss scientists did a study on 250 different animals. They found that the animals' sleeping postures(姿势)had something to do with their body size and weight.

The small animal with short legs sleeps on its stomach. Its body shape is perfect for this posture. It also likes to put its legs under its body. Rabbits and cats sleep this way.

But larger animals sleep differently. 2. They lie on their sides. That's because this is more comfortable for their longer legs. Cows often sleep like this.

However, there are exceptions(例外). Small animals such as mice sometimes sit down to take a short sleep. Some large animals such as horses, zebras and giraffes sleep standing up. 3. In this way, they can quickly escape if they are in danger.

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