Scientists find secret to restful sleep

The secret of how we get a good night's sleep has finally been discovered.

In news which offers hope for insomniacs, scientists have located the chemical which makes the brain send us to sleep.

Researchers discovered the key is a chemical called adenosine, which was found to increase the longer we stay awake.

"Adenosine levels increase when the brain is active over a long period of time," says psychiatrist Robert Green, who led the University of Texas research.

The high levels of the chemical trigger the brain into going into a sleep state, Green's experiments on rats found.

Green also used adenosine-to explain how coffee-helps us stay awake. " Coffee blocks the effects of the brain's own fatigue factor - adenosine - acting on the arousal centre," he said.

The findings could help the 25 per cent of Britons with sleep disorders.