• Question: why do we sleep with our eyes closed?

    Asked by farhanak to Adam, Catherine, Karen, Leila, Nazim on 13 Mar 2012.
    • Photo: Adam Stevens

      Adam Stevens answered on 10 Mar 2012:

      We don’t… necessarily. Some people, like sleepwalkers, can quite happily have their eyes open when they’re asleep, I think.

    • Photo: Nazim Bharmal

      Nazim Bharmal answered on 10 Mar 2012:

      Not sure but there I imagine the brain like a busy computer. To get the day tidied away, it needs to concentrate and when you shut your eyes that is like putting up a sign saying ‘closed’: the brain can then easily ignore light like from the moon or street-lights.

      We don’t “shut” our ears at night. I think the big difference is that the eyes are almost part of the brain, so they are more sensitive.

      Final interesting fact: most birds sleep with only half-their brain at a time, and if you look closely at a duck, for example, only one of their eyes is shut. The other one is keeping an eye out and possibly looking back at you!

    • Photo: Leila Battison

      Leila Battison answered on 10 Mar 2012:

      I don’t think it’s necessary, but it’s pretty common. Even people who open their eyes to sleepwalk will close their eyes to get to sleep in the first place.

      One of the best explanations I have heard: For your brain to get your body to shut down and go to sleep, it needs a chemical called melatonin, which is produced in the dark. Closing your eyes is like it being dark outside, and after long enough, melatonin is produced and you can go to sleep. That also explains why it’s difficult to stay awake in a dark room like the cinema or the theatre sometimes.

    • Photo: Karen Masters

      Karen Masters answered on 13 Mar 2012:

      I don’t know. It’d be a bit bright to sleep otherwise though. My son sleeps with his eyes open sometimes which seems a bit wierd.

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