Do animals sleep? Yes, they do, but not like you. Some nap all day. Some nap for only a little while. Some even sleep underwater.

Bats and lions are big sleepers. A bat sleeps about 20 hours a day, hanging upside down. A male lion sleeps nearly 20 hours a day.

Elephants are the opposite. An elephant sleeps only about 2 to 3 hours a day. A giraffe sleeps mostly at night, then takes quick naps through the day.

Dogs sleep many hours a day, often a third of the day or more. Like other mammals, dogs dream while they sleep.

A horse can doze while it stands up. A sea otter wraps itself in kelp so it does not drift away while it sleeps.

You may have heard that dolphins never sleep. In fact, a dolphin sleeps with one half of its brain resting while the other half stays awake.

Fish need to rest, too. A sleeping fish slows down, and its gills pump less. Some parrotfish sleep inside a bubble of clear mucus.

An elephant seal sleeps about 10 hours a day on the beach. On a deep dive, it takes short naps while it holds its breath.

Hummingbirds can go into torpor at night, which is a deep rest. As of November 2026, scientists say that on a very cold night a hummingbird's metabolism can drop by as much as 95 percent.

Tiny animals sleep, too. Fruit flies sleep. Upside-down jellyfish pulse less at night, so they are less active, too.

Words to know

• torpor: deep rest
• metabolism: body's energy use
• kelp: sea plant
• gills: fish breathing parts