Respect nature's light-dark cycles

In October, the Nobel Prize in physiology or medicine went to three American academics, Jeffrey Hall, Michael Rosbash and Michael Young, for their work on circadian clocks. They've established that plants, animals and humans naturally adapt their biological rhythm - the cycle of rest and activity - so that it's synchronized with the Earth's revolutions, with the cycles of light and darkness.

Their work draws attention to recent changes in the way we live. In the past 100 years, humans have ignored natural light-dark cycles, and relied on electric lighting, particularly screen lights to keep us awake when it's dark outside.

We're just beginning to understand the consequences of this dramatic change in lifestyle. Links have been suggested between a malfunctioning of our circadian clock and both physical and psychological illnesses.