英语文摘:Researchers discover brain chemicals affecting wakefulness

LONDON, July 29 (Xinhua) -- By changing some particular brain chemicals lab mice would become hyperactive and sleep for just 65 percent of their normal time, according to a study released Wednesday by the Imperial College London.

The chemicals, histamine and GABA, are produced in a primitive part of the brain that is highly similar in mice and humans.

Scientists already know the chemical histamine sends signals to the brain to make it awake. The new research suggests that the chemical GABA acts against histamine, like a chemical "brake" preventing wakefulness being too intense.

Researchers from the Imperial College London altered the levels of the GABA produced by the mice's brains and measured what changes this had on their brain activity over the day and night.

They found that compared with normal mice, those without GABA ran twice as far and twice as fast, and maintained or even increased their overall activity over a 30 minute period.

The affected mice also stayed awake much longer in the day, and when they did sleep, the mice experienced just 65 per cent of normal sleep.

"Wakefulness stimulated by histamine may be too much of a good thing, and so the brain has a built in brake on histamine's wake-inducing actions," said Stephen Brickley, who participated in the study.

This discovery could help researchers to develop new drugs that promote better sleep, or control hyperactivity in people with the medical condition mania, according to the study published in the journal Neuron.