Sip coffee to your heart's content and keep diabetes away.

If you're the type of person who perks up in the morning at just the smell of fresh-brewed coffee, you are not alone. There are some laboratory rats you should meet.

While countless studies have looked at what occurs when we drink coffee, far fewer have examined the effects of sniffing the aroma, which contains many volatile compounds.

So Han-Seok Seo of Seoul National University and colleagues exposed stressed-out rats that had been deprived of sleep to coffee bean aroma and then evaluated the effects by performing genetic and protein analyses on brain tissue. They compared the results with tests on other rats, including some that were sleep deprived but not exposed to coffee.

As they report in the Journal of Agricultural and Food Chemistry, they found that the expression levels of 13 selected genes were different between the stress-with-coffee rats and the stress-only animals. With 11 of the genes, levels were higher for the stress-with-coffee group; with the other two the levels were lower. Since proteins are among the products of gene expression, the researchers also identified proteins that were differentially expressed between the two groups of rats. For instance, one protein known to have an antioxidant function had a higher expression level among the stress-with-coffee group. The researchers say the study is a first step toward understanding the effects of coffee aroma.