When we think somebody is having problems coming to terms with reality, we tell them to 'wake up and smell the coffee'

And new research shows that even the aroma of the hot drink does boost brain power. Scientists say just sniffing coffee before an exam could improve young people's grades.

Drinking coffee has long been linked to a host of health benefits - including reducing the risk of cancer, heart disease, diabetes and even dementia.

Now a study has suggested just smelling a coffee-like fragrance - which has no caffeine in it - is enough to boost academic performance.

The unmistakeable aroma increased students' grades in maths by creating an expectation they would do better in tests.

And it could lead to strategies for making people sharper in the workplace - by filling offices with coffee based fragrances or other powerful aromas.

Professor Adriana Madzharov said: 'It's not just that the coffee-like scent helped people perform better on analytical tasks.

"But they also thought they would do better - and we demonstrated this expectation was at least partly responsible for their improved performance."

Her team said it had an effect similar to that of actually drinking coffee.

The finding could lead to improving performance in the workplace - with the use of the alluring smell of coffee or other attractive aromas.

The phenomenon is down a 'placebo effect' of coffee scent - adding to the beverage's perks, said Prof Madzharov.

Previous research has suggested coffee drinkers live longer than those who never touch the black stuff.

But this is the first study to show even its distinctive smell alone could provide benefits.

Prof Madzharov, of Stevens Institute of Technology in New jersey, and colleagues found it helped people perform better on the analytical portion of the Graduate Management Aptitude Test, a test required by many business schools.

Prof Madzharov said it highlights the hidden force of scent.

In the study published in the Journal of Environmental Psychology about 100 undergraduate business students undertook a 10-question GMAT algebra test in a computer lab.

They were divided into groups with one sitting it in a room with a coffee-like scent and the other in an unscented room.

The group in the coffee-scented room scored significantly higher.

But Prof Madzharov and colleagues wanted to know more.

Could the first group's boost in quick thinking be explained, in part, by an expectation that a coffee scent would increase alertness and subsequently improve performance?

The team designed a follow-up survey, conducted among more than 200 new participants, quizzing them on beliefs about various scents and their perceived effects on human performance.

Participants believed they would feel more alert and energetic in the presence of a coffee scent, versus a flower scent or no scent; and that exposure to coffee scent would increase their performance on mental tasks.

The results suggest that expectations about performance can be explained by beliefs that coffee scent alone makes people more alert and energetic.

Madzharov, whose research focuses on sensory marketing and aesthetics, is looking to explore whether coffee-like scents can have a similar placebo effect on other types of performance, such as verbal reasoning.

She also says that the finding - that coffee-like scent acts as a placebo for analytical reasoning performance - has many practical applications, including several for business.

Prof Madzharov said: "Olfaction is one of our most powerful senses.

"Employers, architects, building developers, retail space managers and others, can use subtle scents to help shape employees' or occupants' experience with their environment.

"It's an area of great interest and potential."