Science -- Your Future, Scotland's Future
SCI-FUN Roadshow Exhibits -- Body Clocks
In this exhibit you learn about the clocks that keep your body in time with the day.

Normally we do the same things at the same time every day. We get up at roughly the same time each day, we eat at roughly the same time each day and we go to bed at roughly the same time each day.

We do this partly because we want to fit into our own man-made timetables. But our bodies are also telling us that we want to do this. Our bodies naturally wake up at the same time every day, they feel hungry and prepare our digestive system for food at the same time every day and they start to slow down and feel sleepy at the same time every day.

Body clock #1 -- graphs
Body clock #2 -- graphs
The internal circadian body graphs in the exhibit

Our bodies know what time it is because every single cell contains a clock. To make sure that all the clocks remain in time with each other, our brains contain a master clock, which resets all the clocks daily. This clock uses sunlight to make sure it's the right time. Even some people who are fully blind (but still have eyes) can use sunlight to reset their body clock daily.

Different people's body clocks behave differently. Some people naturally wake up early in the morning and start to feel sleepy early evening. We call these people LARKS. Some people don't wake up until much later, and can stay awake long into the night. We call these people OWLS, Most people are somewhere in between. People change through their lives: children are often larks, teenagers owls and we become more lark-like through our adult lives.

Body clock #1 -- graphics
Body clock #2 -- graphics
The external graphics for the reversable clock exhibit

Our society is organised for people who are somewhere between an owl and a lark. We start work or school at 9 am and finish at 5 pm (that's with homework). Owls are normally too tired to start that early, and larks will be starting to flag mid-afternoon. People often (unfairly) think that owls are being lazy, particularly teenagers, and don't understand that it is their natural body clock.

Modern workplaces often now offer flexi-time, which allows people to fit their work around their family commitments and body clock. Some schools are changing their timetables too, to fit in with teenager's body clocks.

If you're struggling to get up in time for school, just be glad you don't live in the US: many schools there start at 7.30 am.

1 We get up at roughly the ________ time every day.
2 What do our bodies do at the times when we normally eat?
3 Where is our master clock?
4 Are most children owls or larks?
5 How do modern workplaces accommodate different people's body clocks?
6 Do you think you are an owl or a lark? Have you changed at all?

1 During the school holidays, when you have a quiet week, keep a diary of the times you naturally wake up, feel hungry and go to bed. Do you find it's the same times every day?
2 Can you adjust a plant's body clock? Get a pot plant and put it in a cupboard with a lamp. Switch the lamp on and off at a particular time each day, perhaps switch it on at 6 pm and off at 8 am. Can you train the plant to open its flowers in time for when you put the light on, and close them when you switch it off?