Caffeine is the world’s most popular psychoactive drug—ninety percent the world consumes at least one meal or beverage containing caffeine each day. The United States alone consumes 971 tons of caffeine each year, followed closely by Brazil (969 tons). The immense and widespread use of the substance is largely due to its presence in the beans, leaves and fruit of over 60 plants, most of which are cultivated in or exported to most nations on earth. Since nearly 70% of world caffeine consumption is in the form of coffee, it makes sense to examine how the drug affects you at different times of day—morning, afternoon and evening.
The Science Behind Caffeine And Biorhythms
Neuroscientist Greg A. Dunn has recently tackled the issue of chronopharmacology, which is defined as the study of the interaction of biological rhythms and drug action. He suggests that the body’s production of cortisol, a natural steroid hormone, could be an important factor in determining the ideal time to consume caffeine. Cortisol secretion in the human body actually peaks around 8 or 9 a.m. due to a relationship between increased light (daytime hours) and a tiny part of the brain called the hypothalamus, which regulates your circadian rhythm—your body’s 24-hour timing mechanism.
The upshot? Most people choose to drink coffee at a time when they are naturally most alert anyway. This actually increases your caffeine tolerance and encourages you to use more of it in order to achieve your daily caffeine buzz. This means that morning is perhaps one of the worst times to drink coffee!
Cortisol Peaks (And How to Aim Between Them)
That natural morning cortisol jolt isn’t the only daily spike. You also have a medium surge between noon and 1 p.m., and then another small one between 5:30 and 6:30 p.m. (as you may have suspected, cortisol release is also shown to be associated—though not dependent on—mealtimes). Therefore, consuming caffeine during these periods of the day is something of a moot point, physiologically speaking; your body is already generating the energy and alertness you need, so the effect of the drug is wasted (or, perhaps, excessive).
The good news for coffee drinkers? There are many windows throughout the day in which you can maximize the impact of grabbing a cup. The first is between 9:30 and 11:30 a.m., when that morning cortisol peak has diminished. Another is early afternoon, when your circadian clock naturally begins to lag. You’ll recall that the British have historically instituted a small caffeine jolt, known as “tea-time”, for this hour of the day; other countries, particularly Spain, go in the opposite direction and embrace the biorhythmic dip with a siesta or midday nap, choosing to sleep off the day’s least productive hours and make up the time afterwards (Spanish suppers are typically served around 9 p.m.). Just a few of the many fascinating ways our bodies’ natural rhythms have come to revolve around (and against) the pervasive influence of caffeine.
So when it comes to your coffee, you may have to decide if you’re feeling British (embrace the caffeine), Spanish (embrace the biorhythm), or American (throughout the day)!