• Question: Why do we grow more when we sleep?

    Asked by thomasfitz1 to Cathal, Ciara, Emma, Michael, Sive on 11 Nov 2013.
    • Photo: Sive Finlay

      Sive Finlay answered on 11 Nov 2013:

      Hi Thomas,

      There are two main reasons for increased growth during sleep.
      1) Our bodies use less energy when we’re asleep than when we’re awake so the energy that we do use can be spent on growing and repairing tissues. That’s why sleep is so important when you’re sick or injured, it’s the body’s way of shutting down other functions and doing a bit of maintenance and repair work.
      2) Growth is regulated by a hormone which is secreted from the pituitary gland in your brain. The vast majority of growth hormone is only released when you sleep, especially when your brain shifts into deep sleep. So releasing more growth hormone during sleep means you will grow more!
      So the next time you want to lie in just say you’ve got some important growing to do 🙂
      Sive

    • Photo: Cathal Cummins

      Cathal Cummins answered on 13 Nov 2013:

      I don’t know much about the biology of it but from a Physics point-of-view, gravity would have something to do with it too. I know, for example, that astronauts have bone problems (spaceflight osteopenia) in low-gravity conditions due to their skeletons not being compressed. This suggests to me that the skeleton knows when it is lying down so perhaps goes into repair mode(?).

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