Fish don’t sleep in a bed like you do. But they do sleep! (Krieg Barrie)

Fish don’t sleep in a bed like you do. But they do sleep! (Krieg Barrie)

Most fish don’t have eyelids. It’s hard to tell when they are sleeping. (AP/Domenico Stinellis)

Most fish don’t have eyelids. It’s hard to tell when they are sleeping. (AP/Domenico Stinellis)

Parrotfish wrap a cocoon of mucus around themselves when they sleep. (123RF)

Parrotfish wrap a cocoon of mucus around themselves when they sleep. (123RF)

Sharks must keep swimming to breathe, even while they sleep. (NOAA via AP)

Sharks must keep swimming to breathe, even while they sleep. (NOAA via AP)

Dolphins and whales breathe air through blowholes on the tops of their heads. Half of their brains stay awake so they remember to come up for air while sleeping. (AP/Armando Franca)

Dolphins and whales breathe air through blowholes on the tops of their heads. Half of their brains stay awake so they remember to come up for air while sleeping. (AP/Armando Franca)

How Do Fish Sleep?

Posted: November 1, 2022

Honk shoo. Honk shoo. Honk SHOOO . . .

Goldfish in an aquarium. Bass in a lake. Sharks in the sea. The world teems with fish—35,000 species! They swim in springs, rivers, ponds, and puddles. They linger in the darkest depths of the ocean, more than five miles down.

And just like you, they need sleep. God designed sleep so His creatures’ brains and bodies could repair and reset.

But how do you take a sea nap . . . or a puddle nap . . . when a predator could be just around the corner, eager to take a bite? And how do you sleep while you’re swimming?

Scientists are still learning about how fish sleep. What we do know: Unlike people, fish are aware of what’s happening around them while they sleep. They can detect an enemy approaching—most of the time.

Most fish don’t have eyelids, so their eyes don’t close when they snooze. Aquarium fish sleep between seven and 12 hours each day. Study an aquarium closely. A sleeping fish stops swimming around. It remains very still, hovering in the water. Its gills pump less.

Sometimes, fish sleep right out in the open. But often they’re at or near the bottom. If they can, they squeeze into a spot near rocks or plants. That way predators can’t get them. Currents can’t sweep them away. Parrotfish make their own sleeping bags! They wrap a cocoon of mucus around themselves.

Sharks have to keep swimming to keep breathing. They just slow down while they’re asleep.

Whales and dolphins aren’t fish. They have to rise to the surface for air. They sleep by resting half the brain at a time. The other half remembers to come up and breathe!

Why? God created rest for the good of His creatures. We can rest while He controls the world.