A child's body clock is an internal 24-hour rhythm that decides when they get tired, when they get hungry, and when their body temperature drops at night. It runs on its own, whether or not anyone is watching a clock. And in the first week of the school year, it is still running on holiday time.
That is the whole explanation for those heavy August mornings. The alarm clock has moved two hours earlier. The clock inside the child has not been told.
Here is the part that surprises most parents: the body does not set its clock by the alarm. It sets it by light.
Light reaching the eye sends a signal straight to a small region of the brain that keeps track of where you are in the day. When it gets dark, the body starts producing melatonin, the substance that makes you sleepy. When light returns, production stops. It is why a dark cinema makes you drowsy at midday, and why a screen in bed at eleven at night leaves you wide awake.
So the alarm wakes the child. But it moves nothing. The curtains do.
Try it at home: the light log
Divide a sheet of paper into five squares, one for each morning, and pin it to the kitchen wall. Each morning, open the curtains fully before doing anything else, then sit in the light by the window for ten minutes — eat breakfast there, or read. Write down the time, colour the square yellow if it was light outside and blue if it was still dark, and draw a small face showing how hard getting up was, from 1 to 5.
Do it for five mornings. Then look at the five faces in a row.
One thing worth noticing while you do it: even a grey, rainy morning outdoors is many times brighter than the strongest lamp you own indoors. Your eyes do not notice, because they adjust. The body clock notices.
The same lesson runs the other way in autumn, when the darkness comes back and the stars return — we cover that in why we see the stars again.
Questions to wonder about
- Why do you get sleepy when it gets dark, even if you have done nothing tiring at all?
- What happens to the body clock of people who live where the sun never sets in summer — or never rises in winter?
- If your body clock runs slightly slow, and light resets it every morning, what would happen to you in a room with no windows at all, over many weeks?
The heavy week passes. It always does. But it passes faster for a child who knows why it is heavy, and who gets to do something about it themselves instead of just being nagged awake.
Every child is made of good atoms. At Good Atoms, we help them discover it.
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