GERMAN SCIENCE WEEKLY HIGHLIGHT - 4

Your biological clock has no hands, no cuckoo, and it doesn’t chime on the hour. But it ticks, in its own way. In fact, it marks time with a more subtle system than the best Rolex, because it adjusts your body to your environment: for example, to the amount of light outside. Unlike any mechanical clock, your biological clock automatically gives you energy when you should wake up, and takes energy away at bedtime.

"Inside" your clock there are two genes, named Per and Tim. (The clock itself is located – where else? – in your brain; Professor Doyle will tell you exactly where, when you hear the audio below in a minute.) Per and Tim co-operate with two proteins, in a loop like in the picture to the left --click on the magnifying glass to blow it up. When the sun comes out in the day, Per and Tim sense that sunlight. They set the proteins free, and as they work together with cells and organs, this gives you the natural high you need. But when you take a plane from Stuttgart to Santa Barbara – well, Per and Tim get confused. That’s jetlag.

But what’s amazing about Per and Tim is, they can adjust to jetlag. Sooner or later, you get over it. Even though thousands of years ago, when nature made the biological clock, Lufthansa didn’t exist. How do they do it?

The trick is, Per and Tim are a well-coordinated pair. For a long time, scientists didn’t understand why there were two genes – Per and Tim. Why wasn’t it just Per, or just Tim, alone setting the alarm? Your biological clock seemed unnecessarily complex. But that complexity, it turns out, may help you deal with jetlag.

Researchers at the Max-Planck Institute in Magdeburg, Germany, have now used computer models and fruit flies to explain the circadian rhythm genetic circuit. Click the audio and Dr. Joerg Stelling, and Dr. Frank Doyle, whom the Humboldt Foundation helped to join in the research in Germany, will give you a look at the gears of your biological clock.