• Question: How is time represented in the brain?

    Asked by mazzie10 to Damien, Rachael, Simon, Suzi, Tim on 20 Jun 2011.
    • Photo: Rachael Ward

      Rachael Ward answered on 20 Jun 2011:

      hi @mazzie10

      This is a great question.

      Humans have a cycle of roughly 24 hours called the circadian rhythm which is controlled by a group of cells in the brain called the suprachiasmatic nucleus (SCN). The SCN is located in the middle of your head, at about the level of your eyes and receives inputs from your eyes about whether its light or dark to help keep this “clock” in check so you get enough awake and asleep time. A hormone called melatonin is also important for the regulation of circadian rhythm. Melatonin peaks at night and decreases in the day so helps tell your brain how long nights are and is sometime prescribed by doctors to treat insomnia.

      Other organs outside the brain are thought to have their own rhythms but I dont know much about these or if or how the brain is able to judge shorter times – eg how are we able to tell roughly how long 5 minutes is?

      I hope this answers your question a little

    • Photo: Suzi Gage

      Suzi Gage answered on 20 Jun 2011:

      Hi @mazzie10
      I once read about an experiment where if humans are put in an environment with no changes in light levels, so they can’t measure 24 hours by external input, they eventually settle in to a rhythm of a ‘day’ lasting a bit longer than 24 hours.

      This is why, when you go on a long distance holiday, it’s easier to adjust to a day ending up being longer than it should be, that shorter than it should be, which is why jet-lag feels worse when you go west to east.

      That’s the current theory on it anyway. Hope this is interesting!

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