A cup of freshly ground coffee is what it takes to get some people moving in the morning.

But, according to a study, it may be the aroma rather than the coffee itself that does the trick.

Researchers believe that the aroma of roasted coffee beans can soothe frayed nerves - and that just the whiff could be enough to reverse the effects of a poor night's sleep on the brain.

Aroma: Just smelling coffee can help cure tiredness better than drinking a cup

They said that chemicals extracted from coffee and pumped into the air may one day be used as a way of reviving tired people.

Scientists in Tsukuba, Japan, kept 16 laboratory rats awake for 24 hours, by keeping them in a cage filled with an inch of water, then exposed half of them to the smell of roasted coffee.

After taking samples of the rats' brains, they found that the smell of coffee boosted the activity of key genes that promote cell survival in the body and reduce anxiety, New Scientist magazine reports today.

Professor Yoshinori Masuo, who led the study in Tsukuba, Japan, said that when people drink coffee to stay up all night, just the smell of the coffee could alleviate some of the stress caused by sleeplessness.

He added: 'Is it better for us to smell coffee bean aroma than to drink coffee, or would any other food-related odour produce similar effects? Further studies are needed.'

清晨起来，一杯新鲜的研磨咖啡可以让人精力充沛。

但一项最新的研究表明，这种功效可能是咖啡的香气而不是咖啡本身产生的。

研究人员相信，烘培咖啡豆的香气可以安抚紧张的神经-而且只是一点点香气就可以缓解整夜失眠对大脑造成的影响。

香气: 仅仅闻咖啡比喝一杯咖啡更能帮助缓解疲劳

他们说，早晚有一天可以通过提取咖啡中的化学物质并释放到空气中，来缓解人们的疲劳。

日本筑波的科学家们把16只小白鼠放到有1英寸深的水的笼子里，这样保证它们24小时不睡觉。然后，将一半的老鼠放在烘培咖啡的香气中。

在对小白鼠大脑取样后，他们发现咖啡的气味，增强了关键基因的活动，这种基因活动可以促进体内细胞存活，并且减少焦虑。

领导日本筑波研究团队的益男教授说，当人们为了熬夜而喝咖啡时，仅仅是咖啡的味道就会减轻由不睡觉而产生的压力。

他补充说：'闻咖啡豆的气味要比喝咖啡更好。但是否其他食物的气味会产生类似效应呢？这还需要进一步的研究。