New drug developed which can reverse the effects of tiredness

Research in monkeys suggests the drug can temporarily boost mental performance by targeting chemical receptors.

Scientists hope the drug could prove invaluable to shift workers such as doctors and soldiers.

"In addition to improving performance under normal conditions, the drug restored performance that was impaired after sleep loss," said Samuel Deadwyler, who led the study in North Carolina.

The drug was initially tested on normal, alert monkeys. Each was shown a picture on a screen and after a delay of up to 30 seconds, had to pick the original out of a random display of images. The monkeys were then given varying doses of the drug and re-tested.

At the highest dose, the drug improved performance to near perfect for the easier trials and 15 per cent overall. They were then tested after being deprived of sleep for up to 36 hours, the equivalent of 72 hours for humans.

The monkeys' overall performance was reduced under all test conditions, but when deprived of sleep again and retested after being given the drug, their performance was restored to normal levels.

"The drug didn't cause overall brain arousal, but increased the ability of certain affected areas to become active in a normal, non-sleep-deprived manner," said Mr Deadwyler.

The drug, currently known as CX717, has been tested in sleep-deprived humans with positive results, according to the developer, Cortex Pharmaceuticals.

Unlike stimulants such as caffeine, scientists claim it does not make subjects hyperactive or prevent them from sleeping once they have finished working.

The study is published online in the journal Public Library of Science - Biology.