DRINKING a cup of coffee can wake you up, but perhaps just a whiff of Java is enough to reverse the effects of sleep deprivation on the brain.
A team led by Yoshinori Masuo at the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan, deprived rats of sleep for a day. When they examined their brains they found reduced levels of mRNA - messenger molecules that indicate when a gene is being expressed - for 11 genes important to brain function. When the rats were exposed to the aroma of coffee, the mRNA for nine of the genes was restored to near normal levels, and pushed to above normal levels for two - GIR, involved in neuro-endocrine control, and NFGR, thought to control oxidative stress (Journal of Agricultural and Food Chemistry, DOI: 10.1021/jf8001137).
We don't know if the same genes are suppressed in sleep-deprived humans, nor whether we would feel tired if they were, but many of these genes do have human equivalents. So the team says gene suppression may help explain why people feel bad when they haven't had enough sleep - and that gene reactivation could explain why people love the smell of coffee.
Next the team hopes to identify the molecules in coffee aroma that affect gene expression. They suggest pumping them into factories to help revive tired workers who can't sip coffee while operating machinery.