1. First, acquire your coffee. An 8-ounce cup contains around 135 milligrams of caffeine, which is the part you’re really after.
But if you’re buying from a coffee chain, chances are you’re drinking more than that. The smallest cup Starbucks offers, called a “short,” is 8 ounces. The smallest one they actually advertise in store is the “tall,” which is 12 ounces.
2. But hang on a second. Turns out, first thing in the morning might not be the best time to drink your coffee.
You don’t want to drink coffee when the levels of cortisol (a stress hormone) in your body are already high. That’s because cortisol is related to alertness, and levels are high when you first wake up. So you probably don’t need coffee right then (though it might feel like you do).
3. You’re better off having a cup sometime between 9:30 and 11:30 a.m.
Most people’s cortisol levels peak between 8 and 9 a.m., then again between noon and 1 p.m. and 5:30 and 6:30 p.m. Waiting until after the first peak means you’ll be getting a caffeine boost just as your natural alertness is drooping.
5. First it will make you feel less tired and more alert.
Caffeine is similar to a chemical called adenosine in your brain. Adenosine normally binds to certain receptors, causing drowsiness and slowing down nerve cells. But after you drink coffee, caffeine binds to these receptors instead. Caffeine doesn’t cause drowsiness, so it stops you feeling as tired as you otherwise would.
6. Coffee might also make you better at physical tasks that require endurance.
That’s why some marathon runners take caffeine. Be careful though, as there have been a small number of cases of caffeine-taking marathon runners collapsing and dying during races (though no link has yet been shown between caffeine and running fatalities).
7. That is, if you’re not in a state of caffeine withdrawal.
Do you drink coffee regularly throughout the day? Then over time your brain adapts by creating more adenosine receptors for the adenosine molecules to plug into and make you feel tired. This is why you need more and more coffee to achieve the same effect.
When you go too long without coffee, you’ll get withdrawal symptoms. Like a horrible headache. Caffeine withdrawal was even added to the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders earlier this year.
8. In this case, a caffeine boost will just bring you back to a normal level of alertness.
A study published in the journal Neuropharmacology in 2010 concluded that regular coffee drinkers become less alert if they don’t have any coffee, and drinking it just returns them to a baseline level.
10. But it takes between 4 and 6 hours for half a dose of caffeine to be broken down by your body.
So if you drink a 200-milligram cup of coffee at 10 a.m., 100 milligrams of that could still be in your system at 4 p.m.
If you’re an afternoon coffee drinker too, that 3 p.m. cup could still be affecting you as you try to go to bed later that evening.