Wake up and smell the java

Study shows how the scent of coffee relaxes sleep-starved rats

The aroma of freshly roasted coffee may help rats take the edge off all-nighters, a new study suggests. Cells in sleep-deprived rats sniffing freshly brewed coffee turn up the volume of genes that soothe stress and prevent cell damage. The finding suggests one way the smell of coffee may calm stressed-out people — even if the drink itself revs them up.

GET A WHIFF OF THIS After rats pulled an all-nighter, exposure to the aroma of coffee boosted levels of gene products that promote cell survival and help to reduce anxiety. iStockphoto/Bob Gray

Published in the June Journal of Agricultural and Food Chemistry, the study showed that rats exposed to the scent of coffee for 24 hours amped up production of products from genes that encode antioxidants.

The research “provides, for the first time, clues about potential stress-relaxation activities of coffee aroma on a molecular level,” says Thomas Hummel, an otorhinolaryngologist at the Smell and Taste Clinic at the University of Dresden Medical School in Germany who was not involved in the study.

Researchers kept the rats awake for a full day by filling their cages with about an inch of water. “Rats extremely dislike water,” says Yoshinori Masuo, the lead author on the paper and the head of the Mental Stress Team at the National Institute of Advanced Industrial Science and Technology in Onogawa, Japan.

Next, the group put half of the sleep-starved rats in a cage permeated with the aroma of coffee, while the other half stuck it out in a fragrance-free environment. After another 24 hours, rats from both groups were beheaded and their brains ground up for analysis. Masuo and his team measured the levels of gene products and proteins in the brains of both coffee-exposed and normal rats.

Genes that improve resistance to cell damage and promote cell survival were more active in the brains of rats that had whiffed the coffee, Masuo says. The java-sniffing rats also showed a spike in the activity of genes that control anxiety, he adds. These genes may help rein in stress.

While it may be premature for people to start sniffing coffee as stress relief, the results probably can be extended to humans, Hummel says. “Rats are in general much more sensitive to odors than humans,” he notes. “However, as rats and humans are mammals, we do share many features. Especially in the sense of smell there is quite some overlap between the two species, for example, in terms of anatomy or how the brain works with odors.”

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