Whiff of coffee spurs rat race

Smell the coffee and wake up. Scientists now think the mere aroma can be enough to kick-start the brain into action.

Japanese researchers took 30 rats and kept them awake for 24 hours before exposing half to the smell of roasted coffee.

The rats' brain activity was then monitored. Those that had smelt coffee were found to have returned to a normal non-sleep-deprived state of alertness. The smell also appeared to make the rats less stressed, the study, reported in New Scientist, said.

No research had yet been done to see if the findings could be applied to humans.

Peoples Coffee technical manager Dave Lamason, of Wellington, said he often saw people get more animated after smelling fresh coffee. "It's probably the smell of what they are about to consume - the senses going crazy."

Next the Japanese team wants to identify which molecule in coffee has the awakening effect.

They think differences in the way people are wired could explain why some feel so terrible if they don't get a decent night's sleep.

"These results indirectly explain why so many people use coffee for staying up all night," the study concluded. The team has suggested the smell of coffee could be pumped into factories to keep tired workers awake.