No surprise here. Just one cup of coffee takes us from zombie to superhero all before we've finished checking our morning email. But how exactly does caffeine do that, and why does it work so quickly? For starters, it easily bypasses the blood-brain barrier, the central nervous system's built-in barricade to foreign substances. This filter blocks bacteria, viruses and most drugs from entering the brain. But coffee slips through unimpeded. Within 30 minutes, caffeine has infiltrated the bloodstream and every cell in the body. Consider it the Navy SEAL of substances.
Once it's crossed that barrier, it blocks the activity of adenosine, a neurotransmitter that plays a role in making us tired, explains Marci Clow, MS, registered dietician and senior nutritionist for Rainbow Light supplements. "By blocking adenosine other neurotransmitters, we become more alert," she says. "Studies have found that the caffeine equivalent of about two cups of coffee can enhance cognitive function and mood among sleep-deprived people, and affect the specific areas of the brain responsible for memory and concentration."
All of which is good news for those of us wishing to continue our coffee addiction. Bottoms up!