Something like 90% of humans ingest caffeine regularly, making it the most widely used psychoactive drug in the world, and the only one we routinely give to children (commonly in the form of fizzy drinks). Few of us even think of it as a drug, much less our daily use of it as an addiction.
Alas, there is no free lunch. It turns out that caffeine only appears to give us energy. Caffeine works by blocking the action of adenosine, a molecule that gradually accumulates in the brain over the course of the day, preparing the body to rest. Caffeine molecules interfere with this process, keeping adenosine from doing its job – and keeping us feeling alert. But adenosine levels continue to rise, so that when the caffeine is eventually metabolised, the adenosine floods the body’s receptors and tiredness returns. So the energy that caffeine gives us is borrowed, in effect, and eventually the debt must be paid back.
The current scientific consensus is more than reassuring – in fact, the research suggests that coffee and tea, far from being deleterious to our health, may offer some important benefits, as long as they aren’t consumed to excess. Regular coffee consumption is associated with a decreased risk of several cancers (including breast, prostate, colorectal and endometrial), cardiovascular disease, type 2 diabetes, Parkinson’s disease, dementia and possibly depression and suicide.
Caffeine itself might not be bad for you, but the sleep it’s stealing from you may have a price. According to Walker, research suggests that insufficient sleep may be a key factor in the development of Alzheimer’s disease, arteriosclerosis, stroke, heart failure, depression, anxiety, suicide and obesity. “The shorter you sleep,” he bluntly concludes, “the shorter your lifespan.”
But here’s what’s uniquely insidious about caffeine: the drug is not only a leading cause of our sleep deprivation; it is also the principal tool we rely on to remedy the problem. Most of the caffeine consumed today is being used to compensate for the lousy sleep that caffeine causes – which means that caffeine is helping to hide from our awareness the very problem that caffeine creates.