A story is doing the rounds about the coffee aroma and sleep deprivation. But I smell a rat.

It’s an interesting question: can the aroma of coffee stimulate the sleep-deprived brain into action? Yes,

according to researchers in South Korea, Germany and Japan who put rats in a cage with a couple of centimetres of water, forcing them to stay awake. They then put the sleepy animals somewhere dry and wafted the smell of roasted coffee beans under the noses of some of them.

Levels of messenger RNA in the brains of the sleep-deprived rats were reduced for 11 genes involved in brain functio; after smelling the coffee, this function was restored for nine of the genes. It isn’t known if these particular genes have any role in human wakefulness, but the suggestion that the smell of coffee be piped into factories seems to have pricked the imagination of a number of reporters; here, here and here for example.

This story passed across Nature News’s radar a week or so ago, and we contacted a few scientists in the field for their opinions. They pointed to various problems

1) the work doesn’t necessarily show that it’s the coffee aroma in particular that is keeping the rats alert – it could be that it is simply an unfamiliar odour.

2) the rats’ sleep wasn’t measured – it could be that the coffee smell in itself caused further sleep deprivation, meaning that the comparison between sleep deprived rats and coffee-exposed sleep deprived rats isn’t meaningful – the results might have been the same if rats with different degrees of sleep deprivation had been compared.

3) GIR, one of the genes which changed most notably after the sleep-deprived rats sniffed the coffee, is expressed in parts of the brain involved in both smell and stress – so whether it is the stress of sleep deprivation, or the exposure to the smell, is not clear.

So, while it is a neat idea, much more work is needed before we can start inverting “wake up and smell the coffee”.

Image from refracted moments on Flickr, used under a creative commons licence