The best time for coffee is not, in fact, the moment you sluggishly drag yourself out of bed. At least, not according to science. Brainfacts writes that the study of chronopharmacology, aka the interaction between drugs and the body's biological rhythms, reveals when we should and shouldn't drink coffee. More specifically, it dictates the best and worst times to inject ourselves with a peppy dose of caffeine. If your first cup of morning joe comes between 8 am and 9 am, you're doing it wrong, at least according to the study of chronopharmacology.
The body's circadian clock can affect how it responds to drugs, making them more or less effective, altering our tolerance, and so on. Brainfacts writes that light, more than any other environmental stimulus, affects our biological rhythm. That rhythm is controlled by the hypothalamus, which also controls our sleep/wake cycle, hormones, and sugar homeostasis.
The hypothalamus' control of the hormone cortisol is the key that ties together our biological rhythm and consumption of coffee. "Drug tolerance is an important subject, especially in the case of caffeine since most of us overuse this drug," writes Brainfacts. "Therefore, if we are drinking caffeine at a time when your cortisol concentration in the blood is at its peak, you probably should not be drinking it. This is because cortisol production is strongly related to your level of alertness and it just so happens that cortisol peaks for your 24 hour rhythm between 8 and 9 AM on average."
Caffeine will naturally be least effective when cortisol is at its peak, which happens to be right around the time most people drink coffee in the morning.
In other words, caffeine will naturally be least effective when cortisol is at its peak, which happens to be right around the time most people start chugging their morning pick-me-up. Brainfacts goes on to argue that using a drug when it's needed is a key pharmacological principle, and drinking caffeine when it's least effective means you're more likely to develop a tolerance and need to up your dosage.
Drinking a cup of coffee when your cortisol levels are low, on the other hand, will give it some more kick. Cortisol levels apparently swing up between noon and 1 pm, and between 5:30 and 6:40 pm. That leaves a couple windows of opportunity--most importantly, between 9:30 am and 11:30 am or so--where caffeine will really be able to do its job.
One other Brainfacts tip: Since light has a major affect on our biological rhythm and will help cortisol production in the morning, making the morning commute without sunglasses will get the cortisol pumping more quickly. It might not be as stimulating as a cup of coffee, but it's an au naturel way to wake up just a little bit faster.