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 and they have to get to the surface to breathe air periodically.

And a lot of them like everyone's favorite, the bottlenosed dolphin can only hold their breath for seven minutes or so.

So how's a poor cetacean supposed to get some shut eye? Their brilliant answer? Shut one eye at a time.

While sleeping, dolphins let one hemisphere of their brains nod off while the other half keeps an eye out for trouble. Literally. If the left brain is sleeping, the right eye stays open and vice versa.

So they always know when it's time to surface and breathe and when to get to the heck out of dodge.

They seem to switch off every two hours or so until they get a full eight hours a day.

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Assigned 220 times

  • 21jlphal
    10/02/2014 - 11:56 a.m.

    This is just amazing, I thought sleeping with one eye open was a myth! But, dolphins proved us wrong. Just astonishing what mammals, (including us) can do. Amazing!

  • 21gaware
    10/02/2014 - 11:59 a.m.

    I think its very interesting that dolphins sleep with one eye open and one eye closed. I have to sleep with both my eyes shut. It would be very interesting to experience or watch a dolphin sleep. Another thing I think is cool is that dolphins can be underwater without breathing for about seven minutes. I can only be underwater without breathing for about 30-45 seconds.

  • 21BEBROW
    10/02/2014 - 12:00 p.m.

    Dolphins can't sleep on the surface with out swimming if they sleep with half of their brain awake they can still swim but, if they sleep on the surface they can sink and because they will not notice that they are sinking its like if you are asleep can you tell if you roll over on the bed no right ,so they can't tell either.

  • 21pcnaul
    10/02/2014 - 12:02 p.m.

    I think this is amazing because its cool how they sleep compared to humans. It would be cool to see this in real life. Its a good way to protect yourself.

  • 21lktemb
    10/02/2014 - 12:05 p.m.

    I can't imagine how dolphins can sleep with one eye open. I think it's cool how dolphins can do that. It would be awesome if humans could do that too. I think it would be hard to keep one eye open when you sleep though. I don't get how you would get sleep if half of you would sleep at a different time.

  • rosdia20
    10/02/2014 - 12:22 p.m.

    i honestly didn't think dolphins sleep , under water i thought they just float and sleep and wake up when there ready for feel like something is watching him/her . but i think its really cool that they could sleep with one eyes open and still see from it even when there sleeping <3

  • yateri20
    10/02/2014 - 12:22 p.m.

    I think it is amazing how dolphin keep one eye open when they sleep so that way they can see what is coming. I think it would be cool if humans can keep one eye open.

  • merama20
    10/02/2014 - 12:23 p.m.

    I think it is really cool how dolphins sleep with one eye open. I find it really interesting. Also I think its really cool how it switches every two hours or so.

  • carbra20
    10/02/2014 - 12:23 p.m.

    I think its cool how the dolphins sleep like that, its really close to how humans do! I would love to see the dolphins and how they sleep up close.

  • reetod20
    10/02/2014 - 12:24 p.m.

    That's so cool that dolphins can sleep like that, I couldn't sleep with one eye open even if I tried it's just so very crazy!

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