How do dolphins sleep without drowning? (ThinkStock)
How do dolphins sleep without drowning?

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Dolphins aren't like fish, which can breathe underwater.

They're mammals. That means they must get to the surface to breathe air.

They can only hold their breath under water for about seven minutes. That includes everyone's favorite, the bottlenosed dolphin.

So how do these watery animals sleep? They simply shut one eye at a time.

While sleeping, dolphins let one half of their brains nod off. The other half keeps an eye out for trouble. For instance, if the left side of the brain is sleeping, the right eye stays open.

So they always know when it's time to surface and breathe. And when they quickly need to get out of possible trouble.

Sleeping dolphins switch from one side of their brain to the other about every two hours. They do it until they get a full eight hours of sleep a day.

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  • OliviaW-Wal
    10/16/2014 - 02:32 p.m.

    I don't thihk that it's impssble to live unwater because thay have to breth air and so cute

  • patrickf-Bla
    10/17/2014 - 07:32 a.m.

    This article is about dolphins. When dolphin sleep they keep one side of the brain sleeping and one eye open while the other eye is open and the other side of the brain is open. I wonder how they stay under so long?

  • JosephO2005
    10/20/2014 - 04:08 p.m.

    I wish humans could do that. No one could sneak up on you when you're sleeping or in school. One part of your brain could be sleeping and the other half working and when the other half gets tired it can go to sleep and the other part wakes up.

  • OliviaW-Wal
    10/27/2014 - 03:00 p.m.

    Dolphins are mammal they sleep with one eye open becuse they will need to breth and so they don't die

  • TomI-Saw
    11/05/2014 - 12:43 p.m.

    That is so cool I want to be a dolphin now

  • jacksST
    12/04/2014 - 09:43 a.m.

    What a unique way of sleeping under water! Since whales are mammals and are related to dolphins, can whales sleep the same way? Or can they hold enough air in to sleep as long as they need, and to big to get threatened by predators?

  • annabel1226-yyca
    5/04/2015 - 08:38 p.m.

    I think it will be cool if I was a dolphins because I could close one of my eyelids than the other eye keeps out of trouble. Also how do they do that. I can't even do that if I try it I will just fall asleep with all my eyelids close. Also is it really true.

  • JanaN-Saw
    5/28/2015 - 12:17 p.m.

    that looks creepy but that's how they survive thats weird

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