• Question: Why do people get shorter as they grow older?

    Asked by mennie13 to Helen, Jenni, Mark, Martin, Stu on 13 Jun 2011.
    • Photo: Jenni Tilley

      Jenni Tilley answered on 13 Jun 2011:

      Your’e also shorter when you go to bed than at when you wake up (assuming you get out of bed during the day…!)

      The main reason is that your intervertebral disks (the protective disks that sit between the bones in your spine) decrease in size. These disks are made of a material that ‘creeps’ – when you apply a force to it, it gradually stretches more an more, exactly like a blob of silly putty spreading out on the table or stretching when you hold it in the air (Try this at home: http://www.youtube.com/watch?v=Jwv29ZPmuHs)

      When you stand up, gravity pulls the bones in your spine closer together, compressing the disks so that they slowly creep and get thinner, making your spine shorter. When you lie down, the bones return to their original position, so the disks can slowly creep back to their original size, getting thicker and increasing the length of your spine.

      You get shorter as you get older because over time your disks lose their ability to return to their original shape.

    • Photo: Helen O'Connor

      Helen O'Connor answered on 13 Jun 2011:

      Thanks Jenni for that explanation – I had always wondered that myself.
      I also notice than when people are feeling sad, or depressed, their body language and posture match their mood, and they tend to look shorter. And when people feel positive and happy, their posture improves and they seem to “walk tall”. This is one way athletes show their opponents how confident they are – by giving off positive body language.

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